LAS VEGAS — Mike Krzyzewski is working with his team when suddenly Gregg Popovich enters the gym with his own guys looking to play ball.

Krzyzewski vs. Popovich. Five-time NCAA champion vs. five-time NBA champion. It’s a mega matchup that would look good on one of the giant marquees that light up Las Vegas.

Except this is just practice for the 2016 Olympics.

And for 2020.

While Krzyzewski readies the Americans for Rio, Popovich is getting an early start on his own Olympic preparations. The San Antonio Spurs coach is overseeing the Select Team of young players training against the U.S. this week, and some of those players might be in the mix when Popovich coaches the Americans in Tokyo.

“He’s seen what we’re doing and it’s called succession,” Krzyzewski said. “The fact that we’re both military guys, we understand that I have the unit right now, he’s going to take command of the unit, and we both want the unit to do well.”

During practices this week, Popovich works with the young players in one part of UNLV’s basketball complex while Krzyzewski and his staff put the national team through drills in another. Eventually, the Select Team heads into the main gym for scrimmaging.

But Popovich isn’t just here to help the young guys. He’s basically a behind-the-scenes assistant for Krzyzewski.