Maurizio Sarri believes Chelsea's season has been successful so far, as pointed to achievements in cup competitions alongside his side's efforts to finish in the top four.

Maurizio Sarri says Chelsea are in “trouble” as they face a defensive crisis ahead of their Europa League semi-final against Eintracht Frankfurt.

Chelsea only have two fit centre-backs, David Luiz and Andreas Christensen, available for Thursday’s first leg in Germany – after Antonio Rudiger was ruled out for the remainder of the season – while Gary Cahill was not in the 19-man travelling squad.

Cahill, who has only made seven appearances this term, has been ruled out with an Achilles tendon and Sarri admitted the squad’s resources in that position are being tested.

“Cahill is out, a problem with the Achilles tendon. He is out for the moment. I hope to have him back in one week. But he is out, starting four or five days ago. So we are in trouble with the centre-backs.

“In training we played with (Cesar) Azpilicueta at centre-back, in case as he is the only one who can play there.

“It is normal, it can happen that we are in trouble. We have had a lot of games and been lucky with injuries.”

Sarri revealed the club had tried to get Rudiger to play through to the end of the season with his meniscus injury but he was forced off during the 1-1 Premier League draw against Manchester United on Sunday.

“We tried to reach to the end of the season, but the injury was there. He had a problem with the meniscus,” the Italian added.

“We tried to reach to the end of the season, he was unlucky. The situation, with or without the match was the same. At the end of the season he would have had surgery.”

Andreas Christensen has made 29 appearances this season for Chelsea and Sarri is confident the Denmark international is ready to step in.

“I am sure he is ready to play in every match. The only problem is the number. I am confident with Andreas, because he is ready,” Sarri said. “He has played important matches very well.”

Chelsea host Watford in the Premier League on Sunday in a pivotal match for their top-four ambitions and Sarri says the Blues are intent on securing a return to the Champions League through their league finish.

“We need top four in the Premier League, we want to get into the Champions League,” Sarri added.

“It is very difficult to get into top four of Premier League, in the final of League Cup we had to get through Liverpool and Tottenham twice, then City in the final. It’s like a Champions League.”

Azpilicueta says he is ready to change position over the final matches of the season should Sarri face further problems in defence.

“I am ready to play wherever he asks me to play. I have played centre back at Chelsea and the national team. It is true the last couple of months I have been more right back and a few times at left back,” the Spaniard said.

“I can adapt to different positions and enjoy playing wherever the managers think I am useful for the team.”

Chelsea lost the Carabao Cup final in February, and after difficult stages in the campaign, the club have recovered to be in contention for their third European title in the past seven years.

“Here in Chelsea every season we start to go for every trophy. Through the year you can be out of some of them,” Azpilicueta said, when asked of the importance of winning a trophy for the squad.

“We have arrived in the semi-final of the Europa League. It is a long way to be here. To win a trophy it is a priority and that is our aim.”

Get more stories like this on Twitter & Facebook

AD: To get thousands of free final year project topics and other project materials sorted by subject to help with your research [click here]