United are going for their 4th title on the trot, but the 0-0 at Ewood means they are now one point behind leaders Chelsea and the Londoners have a game in hand.
Should Chelsea win that against Bolton then the title looks to be slipping away with only four games left to play catch up.
But Allardyce thinks back to a few weeks ago when Rovers held Chelsea and all the talk then was that Chelsea had blown it.
"We have done a good bit of damage to Manchester United's title hopes," agreed Allardyce.
"But when Chelsea drew here everyone said they were finished. Look what they have done. United might win all four games and Chelsea might slip up somewhere along the line."