Lucas Hernandez could miss the pre-season due to injury. Photo: Christian Hartmann/Reuters

BERLIN Bayern Munich's new record signing Lucas Hernandez may not be fit to start training when he officially joins the club on July 1, coach Niko Kovac has said.

French international Hernandez will become the most expensive Bundesliga player in history when he makes the 80 million euro switch from Atletico Madrid this summer, in a transfer which was announced on Wednesday.

However the 23-year-old World Cup winner underwent an operation this week after his medical examination at Bayern revealed a problem with his right knee. 

"He should be fit for the opening game (of next season), but that doesn't necessarily mean that he will be there for the first day of training on July 1," said Bayern coach Kovac to reporters on Thursday.

"We will have to see how things develop."

Kovac added that the operation had gone "very, very well", and that Hernandez would stay in Munich during his recovery. 

Hernandez can play as either a central defender or as a full-back, and there has been speculation that his arrival could push established centre-backs Jerome Boateng and Mats Hummels towards the exit door at Bayern.

However, Kovac did not specify where he would play the Frenchman next season.

"He is a versatile player, and that is important for any coach," he said. 

"He is a young player, a World Cup winner who can play in different positions and has a good mentality, so he will definitely make us stronger."

AFP