Frank Lampard will miss at least two weeks with the calf injury he picked up in the midweek Champions League defeat to Shakhtar Donetsk.
The 34-year-old midfielder had to be substituted midway through the first half as the European champions lost 2-1 to the Ukrainian side.
Chelsea boss Roberto Di Matteo on Friday confirmed that Lampard would be out for a couple of weeks, meaning he will initially miss the back-to-back games against Manchester United including Sunday's Premier League clash at Stamford Bridge.
Lampard is also expected to miss next weekend's trip to Swansea and the return Champions League clash against Shakhtar on 7 November.
Di Matteo did not put a timeline on a possible return date for Lampard, but it is clear the England midfielder will not be rushed back.
"He is going to be out for a few weeks. He's got a calf problem, so we will miss him and it's a big loss for us," said Di Matteo, who reported no further fitness problems in his squad.
He added: "Apart from Frank, everybody else is fit. Marko Marin might be in the squad for Sunday."
