Manchester United cruised past 10-man Southampton in their FA Cup tie at St Mary's this afternoon to set up a fourth round home tie against Tottenham Hotspur.

A first-half header from Danny Welbeck and a contentious second-half penalty converted by Nani was enough to end Saints' hopes of an upset, which had looked distinctly unlikely from the start and diminished further when they had Matt Paterson sent off in the 36th minute for a violent lunge on United defender Nemanja Vidic. Darron Gibson's third goal rounded off a comfortable win for the champions.

By that point Welbeck had already put the visitors in front, heading in a 20th-minute corner from Nani after John O'Shea's first attempt had rebounded to him off the crossbar.

United dominated the opening half and could have killed the game off had Southampton goalkeeper Kelvin Davis not pulled off a string of fine saves.

Southampton's cause was well and truly lost a minute after the re-start when referee Mike Riley awarded United a penalty for handball against McGoldrick. Oliver Lancashire brought down Welbeck on the edge of the penalty area and when Nani tried to get the ball over the defensive wall, Riley adjudged that David McGoldrick had blocked its path with his arm, though television replays appeared to show the ball hitting McGoldrick's head as he turned away.

Nani took full advantage though when he converted the resultant spot-kick, sending Davis the wrong way.

The victory was completed nine minutes from time when Gibson scored his first goal for the club, volleying in after being set up by Wayne Rooney.