Guus Hiddink has admitted Diego Costa was not fully fit after the striker was forced off with injury as Chelsea crashed out of the Champions League at the hands of Paris Saint-Germain.
Costa missed Chelsea's 1-1 draw with Stoke on Saturday with a tendon injury, but Hiddink brought him back into the team for Wednesday's round-of-16 second leg against PSG.
The move initially paid off as the Spain international cancelled out Adrien Rabiot's early opener, but he had to be taken off in the second half shortly before Zlatan Ibrahimovic scored the game's final goal to take PSG into the last eight of the competition.
"He made a goal, a beautiful goal, but we knew he wasn't totally fit," Hiddink told BT Sport. "But he desperately wanted to play. I must respect that."
Hiddink, whose team must now turn their attention Saturday's FA Cup quarterfinal with Everton, said he will have to wait to discover the extent of Costa's injury.
"We'll see tomorrow," he said. "I hope it will not be a long-term [injury] for Diego.
"But I must say I have respect for him. It would have been better for him if he hadn't have started but he desperately wanted to play."
Hiddink also expressed his disappointment with the way Chelsea approached the game in the early stages but said they improved after Rabiot's opener on 16 minutes.
Costa had levelled for Chelsea 11 minutes later and the Blues had threatened to make it 2-1 and draw level on aggregate, but Ibrahimovic ultimately put the tie out of reach on 67 minutes.
"Of course, we're disappointed," he told reporters after the game. "When you analyse, we started too respectfully in the first 10 or 15 minutes on one hand. On the other hand we're playing against a team that knows how to play a short possession game very well, and you have to be careful not to be outplayed in the first part of the game.
"At 1-0 down, we lost this 'wrong' respect, and wanted to defend a bit more fluidly. We got a deserved equaliser and there were more some chances both ways in the first half. In the second half, we pushed, we tried to get 2-1, we were on the edge around the 65th minute. In the 67th minute, they killed the game."
Asked whether the match was decided in the space of two minutes in the second half, he told BT: "I think that's a correct analysis.
"In the second half we were on the edge of going to 2-1 but it was a little moment in the 67th minute when we had the big chance to score through Willian and others."
Hiddink suggested PSG had triumphed due to a superior squad.
Edinson Cavani, who scored the winning goal after coming off the bench at the Parc des Princes, was again a substitute at Stamford Bridge.
Chelsea, meanwhile, replaced Costa with youngster Bertrand Traore.
"You saw a little bit of difference between the two teams when they had to make changes and Cavani and other big players come in," he said. "I like to bring in young guys but it's different when you have to bring in young guys than experienced players.
"I have to make one exception -- Kenedy was making his debut at left-back and did a terrific job. Nevertheless we lost, and to a very good team."
Chelsea are now facing the prospect of a first season without Champions League football since 2002-03, with the defending Premier League champions currently 10th in the table, 10 points behind Manchester City in fourth place.
"We knew it's a difficult season," Hiddink, who replaced Jose Mourinho in December, said. "When I came in the club was almost panicking that it was in relegation danger. We got out of that in a relatively short time but it's difficult from there to get into the Champions League."
He added: "Chelsea is now in a transition period, they have to see how to go on and try to regain the lost terrain where Chelsea used to be."