The Bees looking good for their lead so far. They scored through the simplest but well-executed long throw routines. And they have held Watford at arm's length since.

The home side have had one really good chance to counter, but Joao Pedro was too slow to shift the ball wide right to a free man before he was tackled.

Norwich fail to pick up Victor Lindelof who is powering forward before squaring to Jesse Lingard on the edge of the box before the move breaks down. It's gone a bit flat inside Old Trafford.

It looks like Martinelli will be fine to carry on for now. One to monitor.

Gabriel Martinelli goes to turf following a perfectly fine tackle from Romain Perraud. He takes a while to get to his feet and moves gingerly afterwards. Losing another forward player to injury and illness is the last thing Arsenal need.

Armando Broja will be an interesting player to look out for this summer. He's done really well during his loan spell at Saints. He's big, strong, quick, knows how to finish.

Well he get a look-in at Chelsea or a what is likely to be a decent-money move?

Saints test Aaron Ramsdale, but he is equal to Stuart Armstrong's shot.

Milot Rashica wins a free-kick deep inside Manchester United's half after being caught by Jesse Lingard. It's a painful one for the Norwich player who is receiving lengthy treatment on the pitch.

The Premier League bottom club are seven points from safety as it stands. They need a positive result.

Just a little lull as regards chances at St Mary's since that Saka chance and superb Forster save.

The quality is just not there for Watford, is it?

They have individuals with ability but they're just not quite up to Premier League class as a side. Juraj Kucka tries to restore parity but slices his effort from range well wide.

A good number of United fans who have been protesting outside Old Trafford are making their way into the ground.

They stayed outside the first 17 minutes of this match - a minute for every year of the owners presence.

That Brentford long-throw routine is off the table.

Ethan Pinnock is off injured, replaced by Mads Bech Sorenson.

Oh what a save!

Yan Valery gives the ball away and Arsenal attack through Eddie Nketiah and then Gabriel Martinelli, who's low ball is perfect for Bukayo Saka to finish.

He does everything right, shooting on target, but Fraser Forster sticks out a hand to divert the ball over. Superb goalkeeping.

Five attempts. Three on target. One goal.

A fast start by Manchester United against the Premier League's bottom club.

Simon Stone
BBC Sport at Old Trafford

The protests outside were noisy but peaceful and intended to continue until the 17th-minute to mark the time the Glazer family have been in charge.

The vast majority were in here for kick-off though. And saw one of the easiest United goals of the season thanks to the Ben Gibson mistake.

Obviously, if the home side win, they are only three points behind Tottenham, so some might ask what are they complaining about.

Evidently, those home fans don't see it like that.

Image source, BBC Sport

Image source, BBC Sport

David Ljungren: and that, ladies and gentlemen, is why Norwich are going down this season. Exhibit 62746373 in Lamentable Footballing Moments from the Canaries

Two Saints corners in quick succession. Both of them dealt with well by Arsenal. Strong work at the back.

Manchester United fans are singing anti-Glazer songs inside Old Trafford. Lots of fans are on their feet clapping in support.

Cristiano Ronaldo's early goal means United are three points off a Champions League spot as it stands.

Arsenal seeing more of the ball, but Southampton are looking to hit quickly when they win the ball.

Romain Perraud drives forward and fires an effort that deflects wide off an Arsenal player.

Chance for Watford. Well, a half-chance.

Moussa Sissoko looks to hit an effort first time from the edge of the box. He mis-hits it but it almost presents a chance to steer home inside the box. Ismaila Sarr and Juraj Kucka don't react quickly enough.

Christian Eriksen just screams class when he gets on the ball. He looks to curl a shot into the bottom corner from range but he doesn't quite wrap his boot around the ball enough and it skips just wide.