Berlin (AFP) - RB Leipzig's coach Ralph Hasenhuettl said Sunday they are investigating why Guinea midfielder Naby Keita collapsed in the dressing room area following their Bundesliga game.

Having played the 90 minutes of Leipzig's 1-0 defeat to Wolfsburg on Saturday, the 22-year-old Keita lost consciousness shortly after leaving the dressing room and was taken to hospital once his condition was stabilised.

On Sunday, the club said all his test results are in order and it is thought the Guinea international suffered a circulatory collapse brought on by exertion, but they want to find out the exact cause.

"He spent the night in hospital and he's feeling better. All the test results are okay," said Hasenhuettl. "It seemed to be the fault of his circulation, he burnt himself out yesterday (during the game).

"For sure, we will continue to look for causes in the next few days.

"It was probably a combination of several factors. "I am glad that there is no deeper disorder. His test results were all okay, that is why we have to look at what was the cause."