Rafa Benitez has revealed that Chelsea captain John Terry's knee injury is "complicated" and the defender could still be some way from a return to first-team action.
Terry has not played for Chelsea since being stretchered off following a collision with Liverpool's Luis Suarez during the teams' 1-1 draw in November.
Since then, the Blues have crashed out of the Champions League, slipped 13 points behind leaders Manchester United at the top of the Premier League and lost in the final of the Club World Cup, while also seeing the departure of Roberto Di Matteo and the arrival of Benitez as interim manager.
Pictures of Terry in action at Chelsea's Cobham training ground on Tuesday have buoyed Blues supporters, but Benitez has expressed caution over those keen to see the skipper back at the heart of the Chelsea defence in the imminent future.
"With John Terry, the knee is quite complicated," he said. "Sometimes it is going well, but the day after we have to wait a little bit. He is closer but I can't say how close. It is getting better."
There was better news on the fitness of Daniel Sturridge, who is back in contention for selection following a hamstring injury.
Sturridge was back in training with the squad following their return from the Club World Cup final in Japan, though he is likely to miss the Capital One Cup quarter-final clash along with the suspended Gary Cahill, Ramires and John Obi Mikel.
Benitez is hopeful his players will be ready for trip to Elland Road despite their long journey.
"We had to train - it's the best way to recover quickly," he added. "A normal training session, not too hard, and we are ready now.
"The players are okay. We have suspensions but in terms of fitness they are fine and available, apart from what we knew before. Daniel Sturridge was training with us - he is fine."