Sir Alex Ferguson's side have yet to play at Stamford Bridge and Lampard says the race for the title remains open-ended.
Lampard insisted: "United have to come here so basically we have to try to win all our games and if we can beat United and they drop points then we have got a chance, it is as simple as that.
"It is far from over. Manchester United know that and we know that but it is important that we try to win our games in the meantime before we play them.
"The win was very important. We were 1-0 down and had we lost we would have been virtually out of the race. We knew that.
"That is why we dug in so hard and pulled it round. The spirit of the lads, especially at 1-0 down, was fantastic."