All over. A huge win for West Ham. They move away from the relegation zone. Southampton are in BIG trouble.

Follow all of the reaction here.

Almost the goal of the season. Joao Mario picks out Aaron Creswell on the edge of the box with the free-kick and the defender's volley at full-stretch grazes the crossbar and goes over.

Three minutes added on. Mark Noble is fouled near the corner flag and West Ham have a free-kick 90m away from their goal.

Simon Stone
BBC Sport at the London Stadium

The build-up to today's game was all about West Ham and their security arrangements.

The post-script is going to very much centre around Mark Hughes and Southampton.

Saints never recovered from that awful start and whilst they might have an FA Cup semi-final against Chelsea to look forward to next month, Hughes is stood on the touchline with his arms folded knowing what a big job he has on his hands to keep his new club in the Premier League.

They have Arsenal and Chelsea in the Premier League next and they finish against champions-elect Manchester City.

Image source, Reuters

It's just a matter of running the clock down now. West Ham replace the impressive Cheikhou Kouyate with 21-year-old Josh Cullen.

Ironic cheers from the home fans. Another simple pass goes straight out of play from Southampton.

Not good.

It's the Southampton fans who are leaving the ground early today. Some of those who have made their journey from the south coast have already seen enough.

Dusan Tadic has a go from 25 yards but his shot dribbles harmlessly wide.

Guido Carrillo comes on for Charlie Austin. Not the return from injury Austin was after.

10 minutes left. This game is done.

Pat Nevin
Former Chelsea winger on BBC Radio 5 live

Kouyate looks fitter and sharper than everyone else out there.

As a midfield duo, him and Mark Noble have been excellent for West Ham and Kouyate will be many people's main contender for Man of the Match.

There'll be no hat-trick for Marko Arnautovic today. He is replaced by January signing Jordan Hugill and gets a huge ovation from the home fans. Everyone is on their feet.

Image source, Reuters

Simon Stone
BBC Sport at the London Stadium

It would take something pretty extraordinary now for West Ham to be deprived of victory.

However, goalkeeper Joe Hart has an incentive to keep the Saints out for the remainder of the game.

A clean sheet would represent Hart's first in the Premier League since September, which given England manager Gareth Southgate is here would be quite well timed.

The one blemish for West Ham today is the injury concern around their players. Cheikhou Kouyate is the latest player to hit the deck and look in discomfort.

They've already lost Antonio remember.

This game has settled down now after Southampton initially looked bright at the start of the half. There looks to be no way back for them. The good news for Southampton is the gap to safety is still only two points thanks to scores elsewhere.

Image source, Reuters

Pat Nevin
Former Chelsea winger on BBC Radio 5 live

It's been a really mature performance by West Ham in the second half.

The first half was committed and entertaining but they have just sat back and controlled the game in the second period.

David Moyes and Stuart Pearce will be delighted.

Mark Hughes does indeed introduce Sofiane Boufal. The Moroccan replaces Nathan Redmond. Gareth Southgate is in the crowd today but there hasn't been too much to get the England manager excited about from Redmond.

Gman: If Hughes can't a tune out of these players after Puel and Pellegrino have tried and failed then the players need to take a long hard look at themselves.

CabbageFace: Keep selling and losing your best players and managers it will catch up on you. Down.

It's no surprise when your team is 3-0 up at home but there is a really good atmosphere at the London Stadium. Another chant erupts around the ground. There are fans on their feet applauding the West Ham performance. How times change.

Marko Arnautovic curls a shot narrowly wide as he searches for a hat-trick.

Image source, Reuters

A snap shot from Joao Mario goes narrowly over as the Hammers threaten seriously for the first time in this half.

At the other end Shane Long continues to look threatening but Southampton are struggling to create.

Mark Hughes has Guido Carrillo and Sofiane Boufal on the bench.

Simon Stone
BBC Sport at the London Stadium

The sun is shining at the London Stadium in more ways than one.

Instead of the ugly scenes we saw when Burnley visited three weeks ago, the West Ham fans are singing, getting behind their own team and taking every opportunity to laugh at Southampton.

The enormity of this victory for David Moyes cannot be underestimated. For Mark Hughes and Southampton though, it is looking like a very tricky end to the season.

Image source, Reuters