The NCAA agreed to change starting times in Nashville, Tenn., and Tampa, Fla., to allow the network to add a fourth game to its schedule Sunday, beginning at about 7 p.m. Normally, only three games are aired on the tournament's first Sunday.
60 Minutes will be pushed to about 9 p.m. EST.
The network announced Thursday that it was to commence coverage of the NCAA men's basketball coverage in the evening with frequent CBS News updates throughout the games.
The network moved the start of its NCAA men's basketball tournament coverage to cable channel ESPN early Thursday.
At noon EST, when CBS Sports' pre-game show was scheduled to start, the network told viewers looking for NCAA action to tune instead to ESPN.
The day's first game, between Marquette and Holy Cross in the Midwest Regional at Indianapolis, tipped off at 12:20 p.m. EST on ESPN with CBS announcers and production.
"Kind of a strange way to start the tournament, isn't it?" CBS studio analyst Clark Kellogg said.
It wasn't immediately known how many games would be shifted to the cable channel or its partner, ESPN2.
"We're prepared to accommodate every window today and tomorrow, if needed. They've sent the first window to us so far," ESPN spokesman Josh Krulewitz said. "Beyond that I don't know. It's a fluid situation."
ESPN is in about 20 million fewer households than CBS is, while ESPN2 reaches about 22 million fewer.
If CBS opted to switch games later Thursday or Friday night, they would be shown on ESPN2. ESPN's previous schedule included NHL coverage Thursday night and NBA coverage Friday night.
"We'll be updating our viewers frequently. We're working closely with the news division," CBS Sports vice president LeslieAnne Wade said.