Southampton win a free-kick out wide on the left. Bertrand sends it deep, Stephens heads it down and Tottenham clear their lines.
90' +3
OVER! Despite the distance, Lo Celso decides to have a go at goal from the free-kick. He lifts it over the wall but it does not dip in time to test Gunn. Poor!
90' +2
J. Bednarek gets yellow.
Bednarek clips the ankles of Son and is shown a yellow card. Further punishment could follow as Tottenham have a free-kick 30 yards out.
90'
Aurier felt Hojbjerg fouled him in the build-up to Boufal's goal but it went to a VAR check and the equaliser was allowed to stand. With four minutes added on here, Southampton will fancy their chances of going on to claim the victory.
88'
E. Dier enters the game and replaces D. Alli.
Dier is on for Alli with two minutes remaining. It is a change Mourinho was looking to make before Boufal's leveller.
87'
S. Boufal has scored a goal for Southampton! Assist by D. Ings.
GOOOOOAAAAALLL!!!!! SOUTHAMPTON 1-1 TOTTENHAM!! IT HAS BEEN COMING! Aurier is dispossessed by Hojbjerg and the midfielder rolls it through for Ings, who in turn squares for Boufal to fire home and surely rescue a replay for Southampton.
Ings has been in hot form in front of goal this season and he showed great awareness to tee up Boufal for this equaliser.
85'
Ings tries to pick out strike partner Adams but his team-mate is unable to bring the ball under control. Tottenham's box is being bombarded.
84'
Mourinho is about to bring on Dier, which looks a smart decision on the face of it. Tottenham are being penned in.
79'
SHOT! Ings is fed by Boufal and quickly gets the ball out of his feet. His long-range shot has Lloris a little concerned but it drifts off target.
Minute
Description
77'
R. Bertrand gets yellow.
Bertrand catches Lo Celso in the neck with an outstretched arm. The Tottenham midfielder, who has been in the wars today, is back to his feet after a bit of treatment. Bertrand will likely be cautioned and nothing else.
Bertrand is shown a yellow card for that elbow on Lo Celso.
76'
Southampton need to settle down after making those two changes in pretty quick succession. Redmond is given all sorts of space down the right and looks for Ings in the middle. Sanchez slips but Ings cannot react in time.
74'
C. Adams enters the game and replaces M. Obafemi.
Hasenhuttl turns to his bench for the final time today as Adams, still without a goal since joining at the start of the season, replaces Obafemi.
73'
Ward-Prowse is tripped up by the referee and that nearly proves costly as Tottenham have a five-on-four counter, but the attack fizzles out on the edge of the opposition box.
72'
Redmond tries to stretch Tottenham before then cutting inside. His cross towards the penalty spot is headed away.
71'
S. Boufal enters the game and replaces K. Danso.
Boufal is on for Danso in Southampton's second substitution of the match. Could that mean a change of formation?
70'
Southampton keeper Gunn comes a long way off his line to get to the ball ahead of Son. He had to get that spot on and did exactly that.
69'
The hosts are not really asking any questions of Tottenham's backline. Mourinho's men are dealing with each cross that comes into the box - it is surely time for Hasenhuttl to change things around.
66'
Tottenham have had just 41 per cent of the ball today but it is they who lead with a little over a quarter of the match to go. Southampton looked lively in the minutes leading up to Tottenham's opener and still have plenty of time to respond, though the game has gone a little flat at the moment.
64'
Tottenham have been on top since edging in front through Son's drilled strike. Mourinho's decision to bring on Lamela for Fernandes has paid off. How long will Hasenhuttl hold off before turning to one of Adams or Boufal?
62'
SON VOLLEYS OVER! Lo Celso lifts the ball over the top of the Southampton defence and Son, having seemingly kept himself onside, gets on the end of the pass. He decides to take on the shot fist time and is unable to keep his effort down.
58'
Son Heung-Min has scored a goal for Tottenham Hotspur! Assist by É. Lamela.
GOOOOOAAAAALLLL!!!!!! SOUTHAMPTON 0-1 TOTTENHAM!!! SON FIRES TOTTENHAM AHEAD! Lo Celso shows brilliant pace and power to carry the ball forward and he plays it into the path of Lamela. The substitute attacker picks out Son, who keeps his composure to fire past Gunn and into the back of the net. VAR will check for a foul by Alli on Danso in the build-up...
Lamela has had a big impact in the FA Cup for Tottenham in recent seasons and he has another assist to his name here after playing in Son.
57'
A miscued shot is nearly turned in by Ings from close range. The momentum is well and truly on Southampton's side with nearly an hour played here.
56'
É. Lamela enters the game and replaces Gedson Fernandes.
Fernandes has struggled at times today and is replaced by Lamela with 11 minutes of the second half played.
55'
Redmond's shot from the edge of the box is closed down. Tottenham are holding on a little at the moment and appear ready to make a change.
51'
SAVE! Danso, who has struggled for starts this season, is rash when trying to tackle Lo Celso and gives away a free-kick 20 yards out. Lucas' attempt is on target but is straight at Gunn.
49'
Neither team has really got going in the opening few minutes of the second half. Lucas has a chance to shoot from 20 yards but he takes too long and is closed down.
47'
Tanganga, who has had another good game today, cuts out Redmond's attempted pass to Obafemi.
46'
RESTART! Tottenham get us back up and running at St Mary's Stadium, where neither manager has made any half-time changes.
45' +2
HALF-TIME: SOUTHAMPTON 0-0 TOTTENHAM
45'
SAVE! Son brings down Obafemi around 30 yards from goal and Ward-Prowse is given an opportunity to test Lloris. The free-kick is on target but Lloris reads it well and gets two hands to it at his near post.
43'
M. Djenepo enters the game and replaces S. Armstrong.
The hamstring injury forces Armstrong off just before half-time. Djenepo is on in his place.
41'
Son leads the Tottenham charge and has options either side, but he elects to go it alone and runs into danger.
40'
Tanganga puts his body on the line to cut out Armstrong's cross. The ball hits him clean in the face and he initially stays down, but he will be okay to continue after a short breather.
39'
Alli and then Son head the ball clear as Southampton build some momentum. Bertrand provides some width down the left but Aurier cuts out this latest cross.
35'
Tottenham have grown more and more into the game and Mourinho will now be wondering how his side have not taken the lead.
32'
Sanchez misses the ball when attempting to cut out a right-sided cross but Aurier does not and Tottenham survive another scary moment. Southampton have got the ball in some good positions but they need to start testing Lloris.
29'
TOTTENHAM GOAL DISALLOWED! Southampton fail to deal with Alderweireld's long pass forward and it causes some panic in the box. Alli does well to lay the ball off to Lo Celso, who picks out the back of the net with his shot. However, the final touch comes off Son right in front of goal and he was stood in an offside position. VAR is going to double check...
27'
Armstrong picks out the run of Stephens in the Tottenham box. The centre-back tries to cushion the ball down to Obafemi but gets the contact wrong and Lloris gathers.
26'
Tottenham win their first corner of the match, which Southampton are able to defend. Alli tries to turn the ball around the corner to Lo Celso from the next attack but it goes out of play for a goal-kick.
24'
Lo Celso's attempted throughball is cut out by Bednarek. This is a rare spell on the ball high up the pitch for Tottenham, but Southampton are remaining compact at the back.
22'
Mourinho's men are far too passive at the moment. Southampton are seeing plenty of the ball in the final third, albeit without creating anything of note thus far.
21'
Armstrong does well to carry the ball forward and Obafemi sends in a right-sided cross towards the near post. Ings stretches out his leg but it goes right through for Lloris to collect.
17'
Bednarek pulls the trigger from range and the ball deflects behind off a Tottenham player for a corner. Ward-Prowse drills it in and Winks is the first one to it at the near post. Good pressure from Southampton.
16'
Redmond cuts inside on his right but delays the shot and eventually plays in Danso, whose cross is cut out for a corner by Tanganga.
15'
Aurier heads the ball forward and Alli races onto it. A heavy touch allows Stephens to cut across the Tottenham midfielder, though, and Gunn collects the loose ball.
13'
Southampton have seen far more of the ball in the early stages but Tottenham have come closest to scoring. The visitors' centre-backs are not afraid to go long when required, as we have seen a lot in recent weeks.
9'
Bednarek goes right through Lo Celso, winning none of the ball, and is fortunate to escape without a yellow card. That was not a good challenge.
7'
Tottenham are happy to back off and allow Southampton possession of the ball. At attempted pass around the back of the visitors' backline is easily dealt with by Lloris, who is making his second start on the bounce after recovering from a nasty injury.
5'
It has been a pretty assured start from Southampton, who are knocking the ball around at the back and into midfield. Redmond has already gone long in the early stages, but he is not afraid to be more direct if required.
3'
An attempted throughball deflects off Bertrand and is collected by Gunn. Tottenham's players feel a free-kick should have been awarded for a back-pass, but the referee points out it was not an intentional pass.
2'
Redmond clips a cross towards the back post from the left and Lloris comes off his line to claim the ball.
1'
KICK-OFF! Southampton, seeking a third successive home win against Tottenham in all competitions, get us under way in this FA Cup fourth-round tie!
Hello and welcome to our live coverage of the FA Cup fourth-round tie between Southampton and Tottenham at St Mary's Stadium.
Southampton were deserved 1-0 winners when these sides met here in the Premier League a few weeks ago thanks to a Danny Ings strike. That triggered a run of four wins in five matches for Ralph Hasenhuttl's men, who are now within three points of today's opponents in the league and will be full of confidence heading into this last-32 clash on home soil.
Tottenham's recent form has been patchy to say the least, having failed to win back-to-back matches in all competitions since November. Even beating Middlesbrough in round three proved a far tougher task than it should have been, with Jose Mourinho's side eventually getting the job done with a 2-1 win in last week's replay after a 1-1 draw in the initial tie.
Subs: Sofiane Boufal, Che Adams, Oriol Romeu, Moussa Djenepo, Harry Lewis, Maya Yoshida, William Smallbone.
SOUTHAMPTON XI (4-4-2): Angus Gunn; Kevin Danso, Jack Stephens, Jan Bednarek, Ryan Bertrand; Stuart Armstrong, James Ward-Prowse, Pierre-Emile Hojbjerg (c), Nathan Redmond; Michael Obafemi, Danny Ings.
Subs: Tanguy Ndombele, Ryan Sessegnon, Paulo Gazzaniga, Eric Dier, Juan Foyth, Jan Vertonghen, Erik Lamela.
TOTTENHAM XI (4-2-3-1): Hugo Lloris (c); Serge Aurier, Toby Alderweireld, Davinson Sanchez, Japhet Tanganga; Harry Winks, Gedson Fernandes; Giovani Lo Celso, Dele Alli, Son Heung-Min; Lucas Moura.
The teams are coming out onto the pitch at St Mary's Stadium, with kick-off just moments away.
Southampton were forced into a change shortly before the break as Armstrong hobbled off to be replaced by Djenepo. Hasenhuttl also has Adams and Boufal among his attacking options from the bench should he wish to gamble, while opposite number Mourinho can only really call upon Lamela in terms of game-changing back-ups.
Southampton and Tottenham play out a 1-1 draw in the fourth round of the FA Cup, meaning they will have to face off again early next month in a replay. Lo Celso had a goal ruled out in the first half for an offside infringement against Son, who got the final touch in front of goal. Lucas and Ings both came close to scoring in the first half but it was not until 58 minutes in that the breakthrough arrived, with Son firing past Gunn after being played in by substitute Lamela. The hosts made a couple of changes and altered formation, a decision that paid off as some late pressure told when Boufal converted Ings' cutback to earn a replay.
Tottenham were within three minutes of advancing through to the last 16, but now Mourinho has an extra fixture to navigate in February. Before that, the north London side host Manchester City in the Premier League next Sunday, while Southampton travel to Liverpool in seven days' time on their return to league action.
That's all for today's live coverage. Thanks for joining!
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