Chelsea boss Mauricio Pochettino has defended their medical staff amid a raft of major injuries.
The Blues were without 12 senior players for last week's draw at Bournemouth.
"It's the profile of the player, the risk of the player. It's not the people working in the medical staff of performance area," said Pochettino.
"I think we need to respect these areas [at the club] are very good professionals, qualified people. That's why they are working in football. But there's an individual risk to [certain] players, you need to assess.
"Then there's bad luck. We have injures that maybe happen in one season or maybe in two, but have happened [to Chelsea] because of different situations you cannot control."
On Christopher Nkunku's preseason injury, The manager also stated: "Christopher against Dortmund, it was a tackle and he twists his knee. Three or four months out. That is from the beginning of the game, he wasn't tired, he was fresh, good, strong," added Pochettino.
"The organisation in football are super professional and we need to respect that. Sometimes things happen like this and it's difficult to evaluate."
