UDPATE 1-NFL-Comeback masters Kansas City end 50-year Super Bowl drought

MIAMI, Feb 2 (Reuters) - 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 to write 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 touchdown 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.

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.

The 24-year-old Mahomes becomes the second-youngest quarterback to win a Super Bowl adding to his credentials as the NFL's next superstar.

Chiefs coach Andy Reid, who had more career regular-season wins (207) than any coach without a Super Bowl, finally got the elusive championship. (Editing by Peter Rutherford)