"We know they are playing well, they've got a very, very potent front three, probably the most potent front three in the country, in terms of pure numbers and goals.
"And obviously Fernandes has made a huge difference coming in in January. So you see the strength that has brought to their team with individual quality.
"But we know that. So we have to be confident ourselves, deal with their threats, and worry about us as well."
Lampard doesnt also think that Chelsea have 48 hours rest more than Manchester United.
"No, I don’t think we do [have an advantage]. We played Saturday/Tuesday this week, they played Monday/Thursday so we have both played two games this week as it stands.
"We are in a period where we are playing games very regularly and it becomes; play, recover, play again and recover and you work with the squad as it is.
"It’s an age-old question for a lot of managers. You can probably dig out times where I have mentioned it, but at the same time it isn’t about having an advantage or not. Sometimes it is in your favour playing regularly and keeping ticking over, so no I don’t see it."
The Englishman also confirmed that N’golo Kante is out of Sunday’s game.
"Kante won't be fit for the match, he's still not right. So he's out.
"Other than that we have a few people with a few little niggles that I'll monitor over the next 24 hours or so, and then we'll be ready to go."