London, Sept 30, 2022 (AFP) - Pep Guardiola says Manchester City's medical staff are the secret behind Erling Haaland's blistering start with the Premier League champions.

Haaland has hit the ground running with 14 goals in nine appearances in all competitions since joining City from Borussia Dortmund in the close season.

Although the 22-year-old was equally prolific at Dortmund, he often found his hot streaks derailed by niggling injury problems.

Aware of those fitness issues, City boss Guardiola has made it a priority to ensure his medical staff keep Haaland fit and firing on all cylinders.

So far, the Norway striker has started every game for City.

"Everyone is important, but I've always said to the club that the most important department in the backroom staff is the physios. They take care of the legs," Guardiola said.

"Erling struggled a lot in Dortmund last season with injuries and arrived here with little problems after a small surgery in the summer.

"He started to work here with (physiotherapist) Mario (Pafundi) and the other guys, and thanks to them - and, of course, his work ethic - he can play regularly now. Last season, it was not possible.

"When the players can play most of the time, it's thanks to the physios."

Pafundi's role is so important to Guardiola that the physio travelled with Haaland during his recent two-week spell on international duty with Norway.

"It's not weird. At events like World Cups and European Championships, many physios go with the players, and Mario is an exceptional physio," Guardiola said.

While Haaland has benefitted from his time with City's medical gurus, fellow preseason signing Kalvin Phillips remains on the sidelines.

The England midfielder had an operation to correct a recurring shoulder problem during the international break after playing just 14 minutes since arriving from Leeds.

Guardiola is hopeful Phillips can return in time for the World Cup.

"He is feeling good. The surgery was really good and the mobility is getting better," he said.

"He took the right decision, otherwise he could not move forward. Now it's solved this problem, and as soon as he is ready, he can come back, hopefully in time to go to the World Cup."

City defender John Stones is also out of Sunday's derby against Manchester United after suffering a hamstring injury with England.

Guardiola expects Stones to be absent for "maybe 10 days, two weeks."