The manager believes Sunday's game at Stamford Bridge will be less end-to-end than the previous meeting between the two clubs at Old Trafford earlier this season
The Red Devils raced into a 3-0 half-time lead in an end-to-end game at Old Trafford, before Fernando Torres pulled one back and went on to miss an open goal in the second half.
"That was a crazy game," the United boss told reporters.
"It could have been 20-18. I don't think it will be like that on Sunday. It will be much tighter."
Despite Chelsea sitting 12 points behind Sir Alex's men going into the match at Stamford Bridge, the Scot remains cautious against a side who United have not beaten away from home in the league for nine years.
"It's not going to be an easy game," he said.
"In the last seven years there have been many terrific battles with Chelsea."
The United manager also believes it will take time for Andre Villas-Boas' style of play to reap rewards at Chelsea.
He added: "The manager has brought in two or three different players and I noticed when we played them earlier in the season there was a change in the style from previous Chelsea teams.
"When a new manager comes in on the back of someone as successful as Carlo Ancelotti, changes maybe take time. Everyone has their different philosophy and different ways of doing things.
"That is what we are seeing with Chelsea at the moment."
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