Kyle Shanahan will now have another Super Bowl collapse to answer questions about.

After being peppered all week by reporters seeking to rehash that blown 28-3 lead to New England three years ago when Shanahan was offensive coordinator in Atlanta, Shanahan's first trip to the Super Bowl as a head coach ended in another late-game meltdown.

The 49ers became the third team in Super Bowl history to give up a 10-point lead in the second half when they blew a 20-10 advantage and lost 31-20 to the Kansas City Chiefs on Sunday night.

"Those guys are hurting in there, just like I am," Shanahan said. "We all are (hurting) right now. It's tough when you lose a Super Bowl, but I'm so unbelievably proud of those guys, what they've done all year. I've been coaching a while and it's as special a group as I've ever been around. It's tough that it had to end today in the way it did."

In two trips to the Super Bowl, Shanahan's teams have been outscored 46-0 in the fourth quarter and overtime and he can only think about what went wrong to cost him two championships.

Shanahan has now had seven drives as a play-caller in the fourth quarter of Super Bowls and his teams have four punts, two turnovers, one failed fourth down and only six first downs.

"We just didn't get it done when we got the ball," Shanahan said. "Came up short on a just couple plays. We had our chance a little bit there at the end, and they made some good plays, and we just missed them."

The 49ers appeared to be firmly in control when they intercepted Patrick Mahomes for a second time with 11:57 to play and a 10-point lead.

But then the coach known as perhaps one of the league's most innovative play-callers couldn't dial up the right plays to help the 49ers seal the win.

Jimmy Garoppolo completed a 12-yard pass to George Kittle to give the Niners a first down with less than 11 minutes to play. But Raheem Mostert was stopped for 1 yard, Garoppolo threw an incompletion on second down and then was forced into a short scramble on third down following a false start on Joe Staley.

That forced a punt and Mahomes led an 83-yard drive that got the Chiefs right back into the game.

"The turning point is we got a turnover and didn't execute on offense," Kittle said. "We gave the ball right back."

The Niners still had a chance to seal it with a productive drive on offense but a first down run followed by two incompletions, including one batted at the line by Chris Jones gave the Chiefs the ball back again.

Mahomes led another TD drive to give the Chiefs a 24-20 edge, setting the stage for Garoppolo to lead a lategame comeback in the final 2:39.

The Niners managed to move the ball across midfield following the two-minute warning before two straight incompletions. Emmanuel Sanders then broke open deep on third down but Garoppolo just overthrew him.

"We missed some shots down-field, some plays we usually make," Garoppolo said. "We just didn't make some of the plays we normally make."

"Pretty brutal," Kittle said. "It's not anything you can wrap your head around. I wish I had another half to play. We didn't take advantage of our opportunities."

AP/XINHUA