MIAMI - The Kansas City Chiefs ended a half-century Super Bowl drought with a dramatic 31-20 comeback win over the San Francisco 49ers on Sunday in a breathtaking finish to the National Football League's 100th season.

With the Chiefs trailing 20-10 in the fourth quarter, quarterback Patrick Mahomes engineered three scoring drives in just over five minutes, hitting Travis Kelce and Damien Williams with short touchdown passes to take the lead.

Williams then raced 38 yards for the clinching score, sparking wild celebration for long-suffering Chiefs fans who had not seen their team hoist the Lombardi trophy since their victory over the Minnesota Vikings in Super Bowl IV.

"We never lost faith, I mean that's the biggest thing," said Mahomes. "Everybody on this team, no one had their head down and we believed in each other and that’s what we preached all year long ... we found a way to get it in the end.

"Those guys around us, the leaders of this team, they have the mindset that we never give up.

"We're going to fight to the end."

San Francisco had looked well on their way to a first Super Bowl in 25 years, holding a 10-point advantage and with time running down, but few leads are ever safe from Mahomes and the explosive Chiefs offense.

In the divisional playoffs, the Chiefs fought back from 24-0 down to beat the Houston Texans and then erased a 10-0 Tennessee Titans advantage in the AFC championship.

"It was a tough loss and hurts everybody in that room," said San Francisco's Kyle Shanahan, who was trying to join his father Mike as a Super Bowl winning head coach. "Kansas City played a good game, they were better than us today.

"We can deal with that but we're obviously disappointed."