Chelsea fear they may have to omit John Terry from their travelling party for the Fifa Club World Cup in Japan, with the European champions' captain still to rejoin his team-mates in full training as he recovers from knee ligament damage sustained in last month's draw with Liverpool.
Rafael Benítez, who has lost Mikel John Obi for three domestic games after the midfielder admitted a Football Association misconduct charge over his clash with the referee Mark Clattenburg, assessed Terry with his medical staff at the club's Cobham training base on Thursday. There remain concerns over the centre-half's ability to twist on the joint injured after Luis Suarez inadvertently landed on his right leg.
Chelsea will have only one more full training session ahead of Saturday's game at Sunderland and are due to fly to Tokyo from Newcastle airport immediately after the match on Wearside.
Should Terry not participate in that final session, he would potentially make the 12-hour journey to Tokyo having not played any part in training for almost a month, and presumably with little chance of featuring in next Thursday's semi-final against either Monterrey or Ulsan Hyundai.
The final could put Chelsea against the Brazilian club Corinthians and is scheduled for 16 December, with Benítez and his staff left to weigh up whether it would be more beneficial for the 31-year-old to remain in Surrey working on his rehabilitation in readiness for the busy Christmas period ahead.
Chelsea play Leeds at Elland Road in a Capital One Cup quarter-final just three days after the Club World Cup final in Yokohama.
A decision will be made on Friday, with Frank Lampard and Daniel Sturridge, who have had calf and hamstring injuries respectively, expected to be passed fit to travel to Japan. Whether they can play at Sunderland remains to be seen.
Mikel will miss the Sunderland match after emerging from a personal hearing in front of an independent regulatory commission with a three-game ban and a fine of £60,000. The referees union, Prospect, immediately revealed its dismay at the "leniency" of the ban incurred after Mikel entered the referee's room after a 3-2 defeat by Manchester United in October and threatened the official in the belief Clattenburg had racially abused him on the pitch.
The commission's independent chairman, Christopher Quinlan QC, stressed it and the FA accepted that "at the time he threatened the referee, the player genuinely believed that the referee had racially abused him" and, had that not been the case, "the suspension would have been significantly longer".
The FA investigated the allegations and found there was no case for Clattenburg to answer. Mikel will also to miss the game at Leeds and the a Premier League game match against Aston Villa.
The grind of Thursday and Sunday fixtures will disrupt established routines, not least with the Londoners due to play away at Manchester City, who are out of Europe altogether, on the Sunday after the second leg of their round-of-32 tie.
"City will be able to concentrate fully on the Premier League and the FA Cup, but I'm sure we will have a good go at the Europa League," said Gary Cahill.
"It's disappointing to have gone out of the Champions League. At Chelsea you're expected to go through the group stage, so it's a blow, but there's nothing we can do about it now. Anyway, I don't think anything could spoil the memory of that night in Munich [in May]. Times like that don't come around in football very often, so it will stick in everyone's minds what we did achieve that night."