Maurizio Sarri hopes Chelsea can tackle a defensive crisis in their Europa League semi-final at Eintracht Frankfurt.

Antonio Rudiger will miss the rest of the season after undergoing knee surgery, while club captain Gary Cahill's hopes of a rare outing have been scuppered by an Achilles problem.

It means Andreas Christensen is set to partner David Luiz at centre-back, with Cesar Azpilicueta ready to tuck into the heart of defence at the Commerzbank-Arena if required, in the absence of any other senior options.

"We are in trouble with the centre-backs," Sarri told a pre-match news conference.

"In the last two training sessions, we played with Azpilicueta as a centre-back in case. I think he's the only [other] one who can play there.

"We've played 58 matches and in the past we were lucky with injuries. In the last 10 days, not so lucky.

"Christensen has played about 25 matches during the season, so he is ready.

"He's played very important matches very well. Christensen isn't the problem. The problem is the numbers."

There is better news further up the field, though, with Willian back in training and fit to play – bolstering wide options that do not include Callum Hudson-Odoi due to his ruptured Achilles tendon.

A 1-1 draw at Manchester United on Sunday kept Chelsea inside the Premier League top four and, although Sarri is focused on lifting the first major honour of his coaching career, he does not want his players to view the Europa League as an insurance policy when it comes to qualifying for Europe's elite competition.

"At the moment, we need to get the top four in the Premier League because we want to play the next Champions League," he said.

"Of course, the Europa League is important. It's a very important trophy. But we need to think about the Premier League.

"We want to get the Champions League through the Premier League. As you know it's very difficult to arrive in the top four in the Premier League."

Sarri was keen to underline a debut season at Stamford Bridge that has garnered mixed reviews stretched his EFL Cup finalists on all fronts.

"If you think that Chelsea, for getting to the final of the EFL Cup, had to play Liverpool in Liverpool, against Tottenham Hotspur twice – Champions League semi-finalists – and Manchester City in the final, it was like the Champions League, only a League Cup in England," he added.

"So it's very difficult to get to the Champions League in the Premier League."