Lampard's absence is softened by the return of captain John Terry, who like Lampard, missed England's Euro 2012 qualifying victories over Bulgaria and Switzerland.
Terry has managed to recover from the hamstring problem that forced him to pull out of the England squad.
"John is available to play tomorrow," said Ancelotti. "Lampard needs to have more time to rest. He trained with us this week and has done very well, but he needs to have more time. Maybe he'll be involved in the Champions League next week but not tomorrow.
"I think these players needed to have a rest because they had problems. Terry resolved this problem during the two weeks. Lampard had to have the surgery. He did very well because, in seven days, he was able to train again. But obviously we want to give him more time to recover 100%."
England's 4-0 success over Bulgaria was followed by a 3-1 away victory at Switzerland, prompting speculation over the international futures of both Chelsea absentees.
But Ancelotti does not agree the pair need to worry about being selected again by Fabio Capello.
"I think Lampard and Terry deserve to play in the national team. I think that, next time, they'll be ready to play for the national team."
Ancelotti also had some words of wisdom for Manchester United's England striker Wayne Rooney - who is expected to be on the receiving end of fan abuse following revelations about his private life.
Terry endured the same treatment last season but the Italian coach believes the United star is capable of taking any abuse in his stride.
"A player who has this kind of problem has to stay focused on the match, on his behaviour on the pitch," said Ancelotti. "If he does that it's not a big problem. When you're on the pitch, you can't think about the behaviour of the fans.
"You have to play football and stay focused on what's happening in the match. Everyone knows how John Terry played last year. Maybe it can be a good motivation if the opposing fans are against you. Rooney scored in the last England game. I think he reacted very well."
Ancelotti also rejected suggestions by Marseille that they had a bid for Didier Drogba turned down by the Blues last month.
"This is not true," added the Italian. "They did not make an offer. They didn't ask the club if they could buy Drogba. If they come to us in January, they already know the answer."
Chelsea go to Upton Park on top of the table with 14 goals scored and none conceded.
The record is in stark contrast to their London rivals who have so far conceded nine goals in their opening three games and scored one goal from the penalty spot.
The poor run has left them rooted to the foot of the Barclays Premier League table and speculation growing over the future of new boss Avram Grant.
But Ancelotti expects the former Chelsea coach to remain calm and lift the Hammers up the table.
"It will be a tough game. West Ham are not in a good moment. They've lost three games. They didn't have a good start to the season.
"Avram has good experience and knowledge about football. He's able to manage the players. West Ham are a club with history and Avram can do a good job there.
"They have a good squad, good players in all positions, so their start is surprising. It can happen when you change a coach, at the start you can have more problems.
"I'm sure that West Ham will have a good season. I don't think they will be involved in the bottom of the table at the end. Not just because of the quality of the manager, but the quality of the players."