Southampton 0-5 Arsenal: FA Cup fourth round as it happened

Full-time: Southampton 0-5 Arsenal

Two the two minutes of time added on here. Can Arsenal grab another?

Perez denied! He's released one-one-one with Lewis but the young goalkeeper makes himself big and makes an important block.

That's the match ball for Theo, then. From his own half, Perez plays a brilliant ball down the left for Sanchez. He draws in two Southampton defenders as he reaches the edge of the box and casually awaits for Walcott to arrive. When he does, the pass to his feet is perfect and he coolly slots home for his third.

Goal! Southampton 0-5 Arsenal (Theo Walcott, 84)

15 minutes left and St Mary's is starting to empty out. This match as a contest ended a while ago.

Here's Arsenal's third change, the impressive Reine-Adelaide makes way for Alex Iwobi.

Another fine goal from Arsenal and Southampton are done here. Oxlade-Chamberlain is again involved, picking out Sanchez who jinks his way down the byline before arrowing a pinpoint cross into Walcott who drives home into the far corner. Easy.

Goal! Southampton 0-4 Arsenal (Theo Walcott (68)

And here comes Alexis Sanchez, he comes on for Welbeck who has enjoyed an outstanding return tonight.

Here are two changes for Southampton, Nathan Redmond and Dusan Tadic come on with Shane Long and Lloyd Isgrove making way.

Alexis Sanchez is getting ready to come on now. You need that when you're three down.

Oxlade-Chamberlain is spraying passes around the pitch like a veteran deep lying playing maker this evening. This time he picks out Walcott but he loses control of the ball as he breaks into the box.

Perez holds the ball up in the box and waits for Bellerin to arrive and strike towards goal, but his effort is straight at the Southampton goalkeeper.

And we are back underway for the second half.

Half-time: Southampton 0-3 Arsenal

Ospina comes leaping out of goal to claim a Southampton cross but the Colombian is left in a heap after crashing into Shane Long.

Brilliant from Arsenal. They ping the ball around brilliantly as they advance into the final third with the Perez and Welbeck again combining neatly on the edge of the box. The Spaniard's ball finds Welbeck who opts to slide the ball across goal from a tight angle for Walcott, who taps home with Sam McQueen nowhere to be seen.

Goal! Southampton 0-3 Arsenal (Theo Walcott, 35)

Højbjerg whips one over the wall but it flies just wide of the post.

Josh Sims looks to be Southampton's best chance of pulling something back here. He harries Holding and wins the ball back 25 yards out from his own goal with Saints eventually winning a free kick as a result of his hard work.

Ospina was almost caught out a moment ago, but he's started to make up for it with a decent save to deny Shane Long. Martina picks out his striker with a brilliant ball curled down the right channel, with the Ireland international smashing his effort towards the near post only to be denied by the Arsenal 'keeper.

Brilliant from Danny Welbeck. Oxlade-Chamberlain picks out his run with a superb 40-yard pass, floating it over Gardos' head and right out the outstretched boot his his teammate. Welbeck keeps his cool and slots it under the onrushing Lewis; his second of the game.

Goal! Southampton 0-2 Arsenal (Danny Welbeck, 21)

Arsenal lead! It's a lovely move, started by Maitland-Niles who slides a pass into Perez, who flicks it first time between two Southampton players and into the feet of Welbeck. It's a tight angle, but the former Manchester United striker waits for the goalkeeper to make his move and brilliantly chips into the far corner.

Slack defending from Southampton who stood off too much there, but very slick from the away side.

Goal! Southampton 0-1 Arsenal (Danny Welbeck, 14)

Maitland-Niles flicks a wonderful ball out to Bellerin who has crept up the right flank past McQueen. He slides a ball into the near post but it's far too close to the goalkeeper who collects, no fuss.

Ospina takes his sweet time over a goal kick and slips over when he does eventually clear, sending it straight into the stand.

Arsenal drive forward again through Reine-Adelaide, who slips a pass through for Oxlade-Chamberlain to run onto. He takes the shot first time, but pings a wayward offer wide of the far post.

Brilliantly play from Reine-Adelaide as he flicks a ball wide to Perez who drills a ball across goal from the left looking for Welbeck. The cross is overcooked however and slips out of play. Bright start from Arsenal.

And Southampton get us started.

We are almost ready to get started at St Mary's, both teams are in the tunnel.

Claude Puel has rang in the changes too for this afternoon's clash. He makes 10 in all to the side that won at Anfield on Wednesday.

With Santi Cazorla, Granit Xhaka, Francis Coquelin and Mohamed Elneny unavailable this evening, Arsene Wenger has opted for a new midfield pairing of Alex Oxlade-Chamberlain and Ainsley Maitland-Niles.

Theo Walcott, Jeff Reine-Adelaide, Lucas Perez and Danny Welbeck all come into the attack with no Mesut Ozil in the squad. Alexis Sanchez is kept in reserve on the bench, where Per Mertesacker has been named for the first time this season.

Southampton team to face Arsenal: Lewis, Martina, Gardos, Stephens, McQueen, Reed, Clasie, Hojbjerg, Sims, Isgrove, Long

Subs: Taylor, Yoshida, Bertrand, Davis, Romeu, Redmond, Tadic

Arsenal team to face Southampton: Ospina, Bellerin, Mustafi, Holding, Gibbs, Oxlade-Chamberlain, Maitland-Biles, Walcott, Reine-Adelaide, Lucas, Welbeck

Subs: Martinez, Jenkinson, Mertesacker, Gabriel, Monreal, Iwobi, Alexis

BREAKING: Danny Welbeck starts his first game for Arsenal in seven months.

Already we've seen how playing a weakened side in the FA Cup can backfire, with Liverpool sent packing by Wolves. Arsene Wenger doesn't seem likely to take the same risk.

We'll put out a team with first-team experience. Maybe there will be one or two younger players, but no more.

"Overall, it's the squad that will play. I have not yet completely decided who will play and who will not play. It's a first-team squad that will be involved.

Do Southampton have Arsenal's number these days? Recent results suggest they just might. Having secured a 2-0 win at the Emirates en route to reaching the EFL Cup final back in November, they have also been a persistent thorn in the Gunners' side in Premier League encounters. Only a stoppage time penalty from Santi Cazorla denied them a draw in north London this season. Last term, the Gunners they failed to beat Saints home or away, drawing in north London and suffering a 4-0 loss on the south coast in the reverse fixture.

Team news: Southampton

James Ward-Prowse and Jay Rodriguez are also unavailable this afternoon with Claude Puel currently dealing with an eight-man injury list.

We have a lot of injuries. Still we are without [Charlie] Austin, [Matt] Targett, [Alex] McCarthy, [Jeremy] Pied, and other injuries with van Dijk and [Jake] Hesketh.

"Also with Jay Rodriguez and James Ward-Prowse not available it is almost a full team. We have possibilities with other players and the rotation since the beginning of the season allows to continue the work and to keep good results.

Claude Puel's side are coming off the back of their historic EFL Cup semi-final final victory over Liverpool, with their 1-0 win at Anfield courtesy of a Shane Long goal securing their place in their first League Cup final since 1979.

The club's resolute performance on Merseyside was all the more impressive given the absence of Van Dijk, the club's outstanding performer this season with 22-year-old Jack Stephens impressively filling the void.

The Dutchman remains unavailable this afternoon, meaning we could see some more of Stephens this evening.

Team news: Arsenal

Danny Welbeck is hoping to make his first start in seven months this afternoon. Wenger said of the England international at his press conference on Thursday:

He has a chance to start or to come on, yes. He looks sharp, he's worked very hard. Maybe it will be an opportunity for him.

Team news: Arsenal

Arsene Wenger has a midfield crisis of sorts on his hands with Santi Cazorla still a long-term absentee and Mohamed Elneny still on international duty with Egypt at the Africa Cup of Nations. Granit Xhaka's ban has hardly helped. The Arsenal boss however is confident a number of his young players can help fill the void if needed.

After [Coquelin and Ramsey], we have Jeff Reine-Adelaide and Ainsley Maitland-Niles, and Alex Iwobi can play in there although he's not a defensive specialist. Those are the options we have.

Team news: Arsenal

Granit Xhaka will not be available for the club's next four games but Theo Walcott is in contention to return from a calf injury suffered at the start of the year.