Ronaldo left Old Trafford this summer to join Real Madrid in a world-record deal and Lampard believes the Red Devils will find it impossible to replace the Portuguese.
The England midfielder feels that it is only Barcelona star Messi who could match Ronaldo's ability for Sir Alex Ferguson's Premier League champions.
And with that transfer highly unlikely, Lampard is confident Chelsea, who resisted the temptation to sell captain John Terry to Manchester City, have an advantage.
When asked about Ronaldo, he said: "You don't replace him, apart from with Messi - he is probably the only player you could do it with.
"With Ronaldo, the amount of goals he scores, the amount of times you flicked on the telly and saw he had scored and they had won 1-0 or 2-0.
Difficult"It is very difficult to replace him. I saw Ferguson say that himself and I don't think he will look to replace him. He will look to make the team as strong as a whole by not having him.
"That is the only thing they can do. That is probably one of our big plusses this year - we didn't lose our big players."
But Lampard believes that Chelsea's hard-fought win over Hull City on the opening day demonstrates that the Premier League is becoming an evenly matched division.
"The league is more competitive this year. It seems teams have found ways to be hard to beat," he added.
"Look at Hull at our place the other day - they were big and powerful and they are looking at a different route of staying up.
"These kind of games have become tough and wherever you go you are in for a very tough game, probably more so than a few years back."