Substitute John O'Shea fired a stoppage time winner to give Manchester United a 1-0 victory at Liverpool and a 12-point lead at the top of the English Premier League on Saturday.

United hardly deserved a victory that came when Ireland defender O'Shea rifled home a loose ball in the area after a Cristiano Ronaldo free kick had been parried by Liverpool keeper Jose Reina.

Victory put United on 72 points, while second-placed Chelsea have 60 before the champions face Portsmouth in the day's late kickoff. Chelsea also have a further game in hand.

United were already down to 10 men when they scored after midfielder Paul Scholes was shown a straight red card four minutes from time after raising his hands at Liverpool's Xabi Alonso.

He will now miss United's next three domestic matches, starting with next Saturday's FA Cup quarter-final against Middlesbrough.

"Today's a massive result for us," United manager Alex Ferguson told Sky Sports News, pointing out that United had also scored their winner in the final two minutes of last Saturday's match at Fulham.

"You need that bit of luck to win a championship, there's no question about that, and I think we've got it in the last two weeks," he said.

The United manager said Wayne Rooney, who made way for O'Shea in the 74th minute, would be assessed on Sunday after suffering a knee injury.

The result was harsh on Liverpool, who had applied nearly all the pressure and whose Wales forward Craig Bellamy had a 50th minute strike disallowed for offside.

But United kept it tight at the back and had a penalty appeal waved away when French substitute striker Louis Saha went down under a challenge from Danish defender Daniel Agger.

Liverpool stay third, with 53 points.