A red card for Saints’ Alexandre Jankewitz after only two minutes triggered a complete collapse for the visitors, who were on the end of the same scoreline against Leicester City in October 2019.
It is only the third time a team has lost 9-0 in the Premier League, with United also beating Ipswich Town by that margin in 1995.
Aaron Wan-Bissaka opened the scoring with his first goal at Old Trafford. Marcus Rashford and Edinson Cavani also found the net on either side of a Jan Bednarek’s own goal before the break.
After a fairly drab start to the second half, United cut loose, scoring five times in the final 21 minutes.
Then, after Bednarek became the second Saints player to be sent off – bringing down Martial to allow Bruno Fernandes the chance to score from the penalty spot on 87 minutes – the French forward netted his second, before Dan James wrapped up the scoring in stoppage time.
It was a stunning ending as United almost matched their club record 10-0 victory over Anderlecht in 1956.
By the final whistle, it had been forgotten that United had come into Tuesday’s game on the back of the indifferent form – just one win in their last four matches.
The massive impact on their goal difference means it is now bettered only by league leaders Manchester City.
Martial should be particularly pleased with his contribution, even though it did not match manager Ole Gunnar Solskjaer’s four-goal salvo as a United substitute in an 8-1 win at Nottingham Forest in 1999.
At one point, it looked as though that seven-goal margin of victory was the one United would emulate. But Martial’s 90th-minute second – the first time he has scored two in a game all season – took the home side beyond that, and James completed the rout in the third minute of injury time.
Rashford and McTominay both produced noteworthy strikes for a United side that also had a penalty award overturned just before half-time.
Man Utd: 6 Feb v Everton (A)
Southampton: 6 Feb v Newcastle (A)