Bayern Munich coach Vincent Kompany will undergo more testing to determine why he collapsed during a training session the previous day, the club said Saturday.
Board member for sport Max Eberl told reporters that Kompany's condition was "stable" and that doctors were focused on "trying to find out" the cause.
"The tests have already yielded some results, but further results are needed to determine exactly what it is and how long it will take for him to recover," Eberl said.
The 40-year-old Kompany was observing a training session for the reserves team when the incident occurred on Friday.
Kompany had been dealing with a viral infection since last week, and his assistant Aaron Danks said on Tuesday it affected the Belgian's legs.
Kompany remained seated throughout Bayern's 6-1 win over Leipzig last week and then missed a training session and a pre-game news conference on Tuesday, when Danks said he needed time to rest at home.
However, Kompany returned to the dugout for Wednesday's 2-2 draw against Arsenal in the Champions League. Following that match, Kompany acknowledged he tried to push through the illness and failed to heed the signals from his body.
Eberl said that he spoke to Kompany and his wife on Friday after he collapsed.
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The executive added that as of now there was no time frame for when Kompany would return, saying it could take weeks.
"He'll only come back when he's fit," Eberl said. "We're not going to start setting any time frames. We need to find out what the issue is, and then it's a question of what the recovery time will be. We're not talking in terms of days, but weeks."
Kompany, a former player, joined Bayern in 2024 from Burnley and has won the German league twice since then. Kompany's team also reached the Champions League semifinals and won the German Cup last season.
He is nominated for the Johan Cruyff Trophy for the best coach of the year to be announced on Monday.
Bayern will visit Freiburg in the Bundesliga on Sunday.