Chelsea boss Jose Mourinho to carefully monitor Diego Costa's fitness

LONDON -- Chelsea manager Jose Mourinho believes that Diego Costa is getting closer to resolving his fitness issues, though he is powerless to stop the striker playing for Spain next month.

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Costa, 25, is unable to play two full games in a week due to a recurring hamstring problem sustained on international duty earlier this month.

The former Atletico Madrid striker has started each of Chelsea's five Premier League games this season, scoring an impressive seven goals in the process, but was forced to sit on the bench for the Blues' opening Champions League Group G 1-1 draw with Schalke before being handed a rest for the midweek 2-1 Capital One Cup win over Bolton Wanderers.

Mourinho confirmed that Costa would lead the Chelsea front-line against Aston Villa this weekend and says the striker is working hard to regain fitness.

"Everyone is working hard. He is the first to do that. He's working hard in his recovery, with the medical staff and the conditioning staff, trying to be ready for every game," Mourinho said.

"Mentally, he's ready for every game. Physically he's not. Everyone is trying hard for him to be able to play every game."

However, the Portuguese coach is concerned that international action could take its toll on Costa when he links up with Vicente del Bosque's squad after the London derby against Arsenal on Oct. 5 for their 2016 UEFA European Championship qualifiers against Slovakia and Luxembourg on Oct. 9 and Oct. 12 respectively.

"It's completely out of my control," he added. Everybody knows that Diego is in trouble for quite a long time.''