The influential Brazilian was sent off in the 34th minute for a high boot against Carlos Alcaraz, breathing confidence into the struggling visitors and making for an open game with good chances at both ends.

Captain Bruno Fernandes came closest for United with a low shot which hit the post, while usually lethal striker Marcus Rashford saw a shot well saved in a one-on-one with goalkeeper Gavin Bazunu.

Southampton missed a string of chances, with Theo Walcott seeing a point-blank header and then a chipped shot both brilliantly saved by David de Gea, while Kyle Walker-Peters hit the post and James Ward-Prowse saw a free kick go close.

United midfielder Scott McTominay nearly skewed the ball into his own goal at one point, only for defender Aaron Wan-Bissaka to scoop the ball off the line.

The result was not what United manager Erik ten Hag wanted after last week's 7-0 drubbing by Liverpool in the league, and was a disappointing follow-up to their scintillating 4-1 Europa League win over Real Betis in midweek.

His team stayed third on 50 points, 16 behind leaders Arsenal but still comfortably placed in the top four positions which qualify for next season's Champions League.

CASEMIRO CONTROVERSY

United fans were incensed by a series of penalty appeals that referee Anthony Taylor waved away. Adding to their ire, the referee had originally given Casemiro a yellow card before changing it to red after a video check.

The Brazilian left the pitch in tears, consoled by countryman Antony.

Casemiro's two sendings off for United in quick succession, after also being expelled against Crystal Palace last month, are the first straight reds of his career.

An irritated Ten Hag criticised "inconsistency" in refereeing and defended the former Real Madrid stalwart's integrity.

"We are Premier League. You want intensity," he said.

"Casemiro is a really fair player, tough but fair. It shows. Over 500 games in big European leagues before, never sent off (with a straight red)."

Though a point at Old Trafford is a creditable result for anyone, Southampton will rue what might have been. The Saints prop up the standings on 22 points, two off the safety zone in a packed fight against relegation.

"I am disappointed with a point but very happy with the performance," said Southampton manager Ruben Selles. "We saw a team playing together, wanting to get something with the game."