London - Jose Mourinho is weighing up whether to risk Diego Costa in Wednesday's Champions League clash against Sporting Lisbon in a bid to improve the Chelsea striker's match fitness.
Mourinho's side are already certain to advance to the last 16 of Europe's elite club competition in first place regardless of the result in their final Group G fixture at Stamford Bridge.
With the hectic Christmas schedule looming, it would be little surprise if the Chelsea manager rests several stars, including the likes of Cesc Fabregas, Eden Hazard and Thibaut Courtois, when the Portuguese club visit west London.
But Costa may not be given the night off to start his Christmas shopping because Mourinho is concerned the Spain international's recent barren run has been provoked by his constant battles with injury.
While Costa hit the ground running after signing from Atletico Madrid, scoring seven goals in his first four Blues appearances, he has netted only twice in his last seven, having been hampered by persistent hamstring and groin problems.
He was easily subdued by Newcastle's defenders when the Blues suffered their first defeat of the season, a 2-1 loss at St James' Park on Saturday.
And although Costa was left out of the Spain squad last month to rest the injuries and was also suspended for last week's victory against Tottenham, Mourinho fears his leading scorer's lack of activity has negatively impacted his performances.
"For me, the problem is not the goals - they will come as a consequence of his condition," Mourinho said.
"He has to improve his condition. He was injured and had many doubts because he went a long time without training.
"Obviously that must have an effect on a player in the way he runs, the way he moves and in his co-ordination.
"I don't think there is any problem but he has to recover."
If Mourinho decides to give Costa the start on Wednesday, he will spearhead a much-changed team, with the likes of Petr Cech, Ramires, Loic Remy, Kurt Zouma and Filipe Luis set to feature against a Sporting side who have a two-point lead over third placed Schalke and can qualify for the last 16 with a draw at the Bridge.
Whatever the line-up fielded by Mourinho, Blues goalkeeper Courtois says the frustration of losing for the first time in 24 matches in all competitions should provide more than enough incentive to treat the Sporting game with total commitment.
"There are only difficult games in the Premier League and we know that. The next game is in the Champions League at home and then against Hull, we have to win in front of our fans," Courtois said.
"Obviously we are disappointed with the result at Newcastle. We tried our best to win this game, and it was a hard game. We were a little bit unlucky.
"At 2-0, it's harder. We tried to fight back, we scored to make it 2-1, but then the ball wouldn't fall right for us and we couldn't draw this game and maybe then win it, so obviously we are disappointed.
"It was a hard game, but we have to stay positive. We are still leaders, but we know these games to be champions you have to win, so from the next game on, we will try our best to win all the games if possible."