Chelsea boss Antonio Conte has claimed that both Willian and Andreas Christensen were suffering with fatigue during the closing stages of the FA Cup quarter-final with Leicester City.
The Blues progressed through to the last four thanks to goals from Alvaro Morata and Pedro, but there was concern after the creative midfielder and the centre-back were withdrawn during extra time.
However, Conte has insisted that the pair were only substituted due to tiredness after the club's trip to Barcelona earlier in the week.
At a press conference, the 48-year-old told reporters: "Willian was very tired, very tired. I think also, today, Willy played a fantastic game with the ball, without the ball. He is in a fantastic physical condition and I'm very pleased with his commitment and his contribution.
"We decided to take this decision because he was very, very tired. But the same for Christensen. He was tired after a game like Barcelona, when we expended a lot of energy, to play 120 minutes tonight with this weather was not easy."
Willian has featured in 45 matches for Chelsea in all competitions this season, while Christensen has played in 36 games.