Denver Broncos head coach John Fox, who was taken to the hospital early on Saturday, will undergo heart valve surgery. 
According to Broncos executive director of media relations Patrick Smyth, the 58-year-old did not have a heart attack as was originally suspected. 
ESPN's Adam Schefter reported that the surgery is for a condition Fox was already aware of:
Denver Broncos coach John Fox is expected to have heart valve surgery this week that could sideline him for up to two months, according to a team official.
Tests were conducted Saturday and will continue Sunday, according to a source familiar with the situation.
Fox was aware that he had a condition with a heart valve that eventually would require surgery. He was hoping to avoid it until after this season but when he experienced the light-headedness Saturday, the timeline for the surgery very well might have been expedited.
As of Sunday night, the team had yet to announce the interim head coach.