Anthony Martial: Kept his role as United's main striker despite the return of Rooney and continued where he left off against Liverpool. Was not always involved in the contest but showed such composure to draw United level before being alert enough to add his second shortly after half-time. Starting to pay off that hefty transfer fee already.
MOMENT OF THE MATCH
David De Gea: Some blamed Sergio Romero for both goals United conceded in defeat at Swansea but De Gea is now back between the sticks and his save from Fonte in the second half showed why he is considered one of the best goalkeepers in the world. As good as a goal for the Red Devils, who again had their Spanish number one to thank for playing a key role in a win.
VIEW FROM THE BENCH
Neither Louis van Gaal nor Ronald Koeman has ever tasted home league success over the other and their simmering rivalry continued with old master van Gaal coming out on top. Koeman would have been disappointed to surrender a lead his side should have built upon whereas the United boss saw his side move up to second in the table after a comeback victory.
Southampton 2 Manchester United 3 player ratings
Southampton 2 Manchester United 3 player ratings
1/21 Southampton: Stekelenburg: 5/10
The Dutchman was not helped by his defenders, but did not have the look of a composed man. Not a worthy replacement for Fraser Forster.
2/21 Yoshida 4
Right back is not his favoured position and it showed. Produced a criminal back pass to gift Martial the opportunity to score his second goal.
3/21 Fonte 6
A leading light in Southampton's back line. The only remaining member of last season's tight knit rearguard, he is a level above the rest.
4/21 Van Dijk 5
The defender is quickly discovering that the Premier League is not comparable to the north of the border. Struggled and lucky not to be dismissed for a petulant foul on Martial.
5/21 Targett 5
Substituted at half time after struggling to contain United's forages forward on the right flank.
6/21 Wanyama 6
The enforcer was not at his best but still helped to smother plenty of United attacks. However, couldn't link to the front men as well as he would have liked.
7/21 Romeu 5
Struggled to get a foothold in the game. The Spaniard must improve if he is to fulfil his potential at St. Mary's.
8/21 Mane 6
A constant menace. Few defenders seem to have figured out how to stop him and he produced a superb assist for Pelle's second.
9/21 Ward-Prowse 6
The English youngsters boasts superb delivery from wide areas and did not disappoint. Needs to do more to cope with the physicality of the division.
10/21 Tadic 6
Encouraging early on, but the midfielder's display fizzled out somewhat. His crosses did not dip in quality but he did not have the impact that his start suggested he would.
11/21 Pelle 7
A simple tap in for the first goal, which he took well, and nodded home superbly for his second. Would have had a hat trick but for the width of the post.
12/21 Manchester United: De Gea 7/10
The safest pair of hands in the division. Exposed by his poor defence on countless occasions but still made several smart stops.
13/21 Darmian 5
Withdrawn at half time due to injury. If the Italian's absence is an extended one he will be sorely missed given the impressive start to his career in England.
14/21 Smalling 5
All at sea early on in a throw back to the dark days. Struggled to cope with Pelle's power and the fluid nature of the remainder of Southampton's attack. A dip after what has been a stellar start to the campaign.
15/21 Blind 5
Although the Dutchman is composed on the ball his lack of pace is strikingly obvious. His ability can get him our of trouble at times but his snail-like speed can be his downfall at centre back.
16/21 Carrick 5
The Englishman's strengths do not seem to sit well with Schneiderlin's. Sat deep but looked off the pace. He is far from an enforcer and his composed - but safe - patterns of passing did little to affect the game.
17/21 Schneiderlin 6
Appeared to be somewhat affected by the return to familiar surroundings. Received a bit of jib from the home crowd but still managed to pass the ball impeccably.
18/21 Mata 6
Debate continues in regards to the Spaniard's best position, though the right flank is not alien to him.
19/21 Rooney 6
Distinctly average. The skipper was deployed at number 10 and covered plenty of ground but did not provide the cutting edge in the final third that he is constantly expected to command.
20/21 Depay 6
It just isn't happening for the Dutchman. He is desperate to make something happen but his powerful runs and ability on the ball are yet to yield a final product. Struck the post in the build up to Mata's goal.
21/21 Martial 8
The teenager has answered his critics emphatically. A well-taken brace courtesy of two composed finishes had the appearance of a man with far more experience than the 19-year-old. His instant impact goes from strength to strength.
MOAN OF THE MATCH
Wayne Rooney still is not quite at it for United this season. Van Gaal deployed his skipper in the hole behind Martial but he was a peripheral figure for much of the game and was never a goal threat. The pressure of getting the goals has been taken off of his shoulders but he will need to show he still contributes to the side in other ways.
WHO'S UP NEXT
MK Dons v Southampton (Capital One Cup, September 23)
Man Utd v Ipswich (Capital One Cup, September 23)