United rewrote the history books with a 12th successive top-flight clean sheet
Sir Alex Ferguson believes his table-topping Manchester United team hold a slight advantage in the title run-in, but warned against complacency.
United beat Everton 1-0 to move five points clear at the top of the league.
"It is an advantage, but I can't say it is a great advantage with 16 games left," said the United boss.
"We have a difficult game away against West Ham next week and there are a lot of difficult games in the run-in and teams will drop points."
I couldn't believe it when I read the last goal we conceded was against Arsenal way back in November
Sir Alex Ferguson
Cristiano Ronaldo's 44th-minute penalty, awarded for Mikel Arteta's challenge on Michael Carrick, earned United a deserved victory against a resilient Everton.
The win moved United five points ahead of Liverpool and Chelsea, who meet on Sunday, and Ferguson admitted he was hoping for a draw at Anfield.
"It is always better to be top of the league than anywhere else," said the Scot.
"We just hope we don't drop as many as the rest. I'll be looking for a draw on Sunday."
The win over Everton saw United rewrote the record books with a 12th successive top-flight clean sheet , with goalkeeper Edwin van der Sar eclipsing the previous league record of 1,104 minutes without conceding a goal, set by Reading's Steve Death in 1979.
The last player to score against Van der Sar was Arsenal's Samir Nasri in the Gunners' 2-1 victory at the Emirates on November 8.
And Ferguson said: "It is fantastic. I couldn't believe it when I read the last goal we conceded was against Arsenal way back in November - that's incredible."
Ferguson believed referee Mike Halsey made the right decision to award the penalty against Arteta and said his side should have been awarded a second spot-kick for Joleon Lescott's second-half challenge on Carrick.
He said: "It (the first challenge) was inside the box and I don't think Arteta tried to but he has clearly brought him down and it was a penalty.
"I think the second was a clear penalty, no question about it. It was more of a penalty than the first one but you are not going to get two penalties, let's be honest.
"I think we had a lot of chances in the match but we never put Everton to bed. A second goal would have put the result in our favour without question.
"If you are not taking that second chance you are not sure of the game and Everton kept going because of that, showed great resilience and athleticism and took it right to the wire."
Everton manager David Moyes did not believe Arteta's challenge on Carrick was a penalty.
"They stuck at it. In the first half we needed our goalkeeper (Tim Howard) to be inspirational to keep us in it," said Moyes.
"We were playing against a good team and you need a bit of luck and it might have gone against us in the penalty."
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