Maurizio Sarri believes Ruben Loftus-Cheek will never truly overcome the back problems that have frustrated his senior career and will always need to follow a personalised fitness and training programme to maximise his game time.

The England midfielder has been a regular in Sarri’s Chelsea side since recovering from his latest back spasms in January and, although he has made only five Premier League starts, has managed 39 appearances for club and country this season. That represents his best return – a successful loan at Crystal Palace last term saw him ruled out for almost three months with a heel problem – on the back of the World Cup.

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Yet Chelsea have to monitor his fitness. The 23-year-old has a curve in the spine in his lower back has suffered muscular spasms since he was a teenager and, along with a specific training routine, has taken up yoga in an attempt to manage the problem.

“I don’t think he will need surgery,” said Sarri, who watched Loftus-Cheek put in a dominant performance in the Europa League draw with Eintracht Frankfurt on Thursday. “We have to control him. He needs, probably, a particular way of training for sure. I think [he will suffer the problems] for a long period, probably for ever. But we can avoid an operation. In the last month he has been able to train every day so, for us, it’s really very important. Now he is fit and, in Germany, he played very well before suffering from cramp. That can happen of course. But I am really very happy with him.”

Loftus-Cheek is likely to be called up to Gareth Southgate’s England squad for the Nations League in Portugal, where England will play twice next month. “I will be happy for him [if he is selected],” said Sarri, “but I think it is better for him to try to recover completely.”

The midfielder is expected to be one of the changes to the lineup for Sunday’s game against Watford as Chelsea seek the first of two victories which should secure Champions League qualification via the league. Eden Hazard, who came off the bench in Frankfurt, will start potentially his last top-flight game at Stamford Bridge amid Real Madrid’s long-standing interest. A lack of defensive options means Sarri will retain Andreas Christensen alongside David Luiz at centre-half.

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The latter is out of contract in July but his representative held talks with Chelsea last week over a new deal. It remains to be seen whether that ends up as a 12-month extension, maintaining the club’s policy for players over the age of 30. “For us, David is a very important player,” Sarri said. “Also in the dressing room. You know very well my opinion, and then there is also the opinion of the player and the club, but I think we can solve this situation in the last couple of weeks of the season. I am confident.”