ENGLEWOOD, Colo. >> Denver Broncos coach John Fox underwent heart surgery Monday in North Carolina, team Executive Vice President John Elway said.

Elway said he hasn’t received an update yet.

Fox underwent aortic valve replacement surgery while defensive coordinator Jack Del Rio was running practice after being named interim head coach.

Elway said he knew Fox needed a heart operation, which had been scheduled for after the season.

Del Rio was named interim head coach Monday when the Broncos returned from their bye. He will remain Denver’s defensive coordinator while running the team for several weeks while Fox recovers.

Like Fox, Del Rio’s roots are on the defensive side of the ball. This is his 17th season coaching in the NFL following an 11-year playing career with the Saints, Chiefs, Cowboys and Vikings.

That includes eight-plus seasons as head coach in Jacksonville, where he was 69-73, including 1-2 in the playoffs from 2003-11. The Jaguars haven’t been anywhere near competitive since his dismissal in 2011.

Del Rio joined Fox’s staff last season — he also served as Fox’s defensive coordinator in Carolina in 2002 — and the Broncos ranked second in the league in yards allowed a year after ranking dead last in the league.

The Broncos are ranked 24th in defense this season, but they were missing star linebacker Von Miller and cornerback Champ Bailey for much of the first half of the season and are coming off their best performance of the year in a 45-21 win over Washington last month.

Fox was hoping to put off his operation until the offseason but after meeting with his cardiologist in North Carolina late last week, he began feeling dizzy while playing golf near his offseason home in Charlotte on Saturday and was hospitalized.

The Broncos (7-1) play at San Diego on Sunday as they seek their 19th win in their last 20 regular-season games.

While pulling double duty, Del Rio will rely on other members of the coaching staff to pitch in, men such as linebackers coach Richard Smith, a former defensive coordinator, and running backs coach Eric Studesville, who served as Denver’s interim head coach following Josh McDaniels’ firing late in 2010.

He’ll also rely on his captains, particularly Peyton Manning and Wesley Woodyard.

Del Rio has long commanded the respect of his players, who appreciate his resume as a star NFL linebacker. He’s a lot like Fox in that he’s considered a player’s coach, one who understands things from their perspective.

Although they have similar philosophies, backgrounds and approaches, Del Rio’s sideline demeanor can differ from the easygoing Fox’s. At Indianapolis, he dressed down Bailey for his abysmal coverage on a touchdown pass just as vehemently as he castigated rookie linebacker Danny Trevathan for fumbling a pick-6 at the goal line in the season opener.