Mourinho believes it was exacerbated by playing against Slovakia and Luxembourg during the international break this month and took a swipe at Spain boss Vicente del Bosque.

“It’s the same problem that he’s having, but now an injury, not an almost injury,” said Mourinho, who is uncertain when Costa will return.

“It’s simple. He’s not training because he’s not in condition to do it.

“Tomorrow he cannot play. Let’s see what happens for next weekend, but next weekend is not important.

“I don’t have Manchester United (on Sunday in the Premier League) in mind. I have Maribor in mind.”

Costa has scored nine goals in seven Premier League games, but was absent for Saturday’s win at Crystal Palace.

Chelsea have the same squad as at Palace for their first fixture with a Slovenian side, with Nigerian midfielder John Obi Mikel (foot) absent and Brazil midfielder Ramires (groin) and World Cup winning German forward Andre Schurrle (illness) also missing despite training on Monday.

It is the situation regarding Costa which appears to be frustrating Mourinho most.

He added: “Sometimes you have national coaches and medical departments that want to establish a relationship and they are interested in the players, their physical condition, their habits.

“Some others they simply don’t care. This is not something we can resolve.

“In this moment, since the beginning of the season, I think from all the national teams, I think (I have received) one phone call from Roy (Hodgson, the England boss).”

Mourinho declined to reveal details of the conversation with Hodgson, but defender Gary Cahill was carrying an ankle knock at the start of September prior to England’s match with Switzerland.

The Portuguese revealed how then Croatia boss Igor Stimac called him three times a week about midfielder Luka Modric when he was Real Madrid boss as an example of communication.

“It hurts,” Mourinho added.

“You are not happy when you give players in good conditions and you receive the players in bad conditions.”

Mourinho has not spoken to Del Bosque regarding Costa and was adamant the situation was out of his control.

He added that he would not try to exert pressure on his players to pull out of internationals.

“It’s something that is out of our hands,” Mourinho added.

“I had in my career a few of them in permanent contact with me.

“I had others where, year after year after year, I don’t have one single SMS (text message) or one single phone call. It depends on them.

“I’m not the kind of guy to tell the players not to go. I don’t tell the players to pretend they have problems.

“I like the players to go. Our club likes the players to go and we like our players to succeed in the national teams, to play in big competitions.

“The players should be proud to play for the national teams and Chelsea Football Club is proud that our players are selected for their national teams. We don’t change our approach to the situation.”

Didier Drogba has shaken off an ankle problem and could feature, although not for 90 minutes, with the Ivory Coast striker vying with Loic Remy for the starting spot up front in place of Costa.

Mourinho recently spoke of his team being built with Costa as the attacking focal point and refused to discuss adjustments with a different striker in place.

“Drogba, Remy and Diego are different,” Mourinho said.

“You speak about Diego, I don’t speak about Diego. I say to my players: ’I don’t want to speak about injured players’.

“When somebody is injured I always look at it as an opportunity for another player. When he’s not here, he’s not here.”

Maribor have drawn with Sporting Lisbon and Schalke in their opening two matches – Chelsea won in Portugal last time out, having opened with a home draw against the Germans – and Mourinho is not underestimating a team which reached the group stages at Celtic’s expense.

“The results tell you a lot,” Mourinho said.

“The results away from home have been very impressive. I think they are a difficult team.

“We worked today studying them and I’m happy because my players now have the feeling that they are a difficult opponent.”