Pedro will be sidelined for Chelsea's trip to Crystal Palace in the Premier League on Sunday, with the game live on Sky Sports.
The Spain forward limped out of the 2-1 Boxing Day win at Watford with a hamstring problem, and could now be absent for two weeks.
Eden Hazard is set to continue in the false-nine role he has played in recent games, despite admitting that he prefers playing on the wing.
Speaking about the positional change, Blues manager Maurizio Sarri said: "I cannot see the problem of Hazard in this role, he played four matches as false number nine, and he scored three goals and two assists.
"I am really very happy with him in this position because he's very able to score, first of all, but he's very able to open spaces for the team-mates, to come and play with the team-mates.
"So at the moment I am very happy with him in this position, but in the future he can also play as a winger of course."
Roy Hodgson's Crystal Palace side shocked Chelsea 2-1 at Selhurst Park last season - their first win of that campaign - but he is well aware that result will have little influence on their chances this time.
He said: "Against Chelsea a little bit of fortune came our way. It was a spur for us because it showed us, not only are you on the right track but if you get the bounce of the ball, we can win games, even against the champions of England, as Chelsea were at the time.
"Very pleasant memories but that was then and winning a game last year is absolutely no good to you winning it this year! They are doing very well in the league and will be a tough ask for us."
Team news
Callum Hudson-Odoi will face a late fitness test after picking up a hamstring injury of his own at Watford, while Alvaro Morata is fully fit.
Hodgson reported no new injuries for Crystal Palace, with Wayne Hennessey (back), Cheikhou Kouyate and Martin Kelly (adductor) back in contention. Christian Benteke is the only player still unavailable.
Opta stats
Crystal Palace have won two of their last four league encounters with Chelsea (L2), as many wins as they'd registered in their previous 18 combined (W2 D4 L12)
Chelsea lost in this exact fixture last season (1-2) - they've never suffered consecutive away defeats against Crystal Palace in league competition.
Chelsea are winless in their last five away Premier League London derbies (D2 L3), their longest run without a win on the road since a run of eight between December 2010 and September 2012.
Crystal Palace have won more points in their last three Premier League games (7) than they had in their previous 11 in the competition (6).
Chelsea are looking to win three consecutive Premier League away games for the first time under Maurizio Sarri, last doing so in April when Antonio Conte was in charge.
Chelsea star Eden Hazard has been involved in more goals than any other Premier League player coming into this weekend (19 - 10 goals, 9 assists).
Crystal Palace boss Roy Hodgson has enjoyed three victories in his last four home games against Chelsea in the Premier League (L1), achieving wins with Liverpool in November 2010, West Brom in March 2012 and with the Eagles in this fixture last season.
Merson's prediction
They are a bag of Revels at the moment, Chelsea - you don't know what you are going to get. They go and beat Man City at home, then they go and get beaten by Leicester at home. I just don't think Palace have the goals in them to get anything from this. The form that Eden Hazard is in at the moment I cannot see anything other than a Chelsea win. It will be a hard game, because Palace can make it hard for teams, but Chelsea will have too much.
PAUL PREDICTS: 1-2 (15/2 with Sky Bet)