Gary Cahill is worried that tiredness is negatively impacting on Chelsea's performances as they look to avoid a potential fixture pile-up of four games in eight days.
If Rafa Benitez's side draw with Middlesbrough in their FA Cup fifth-round encounter on Wednesday, the only available date for a replay would be March 4, just two days after they are due to play West Brom in the Premier League and only three days before a Europa League tie against Steaua Bucharest.
The Blues have already played 47 games in a gruelling season, more than any other team - competing in eight different competitions including a trip to Japan to take part in the Club World Cup.
And Cahill admitted that fatigue is starting to become a factor, telling Chelsea TV: "Unfortunately it does take its toll. We haven't had a clear week for about 29 weeks and you're expecting to go into games feeling 100% fresh, trying to push on further in all competitions.
"I think at this stage of the season, it is not an excuse, but fatigue has to play a part."
With Chelsea's Premier League title hopes all-but gone, their targets for the season remain a trophy - with the FA Cup and Europa League still up for grabs - and qualification for the Champions League.
"We've got two cups and obviously trying to get the Champions League spot. That is our aim from now until the end of the season," Cahill said. "All three are in our own hands so we need to keep going and plug away and make sure we achieve the goals we want to achieve."