Ireland’s Padraig Harrington has won his first US PGA title in seven years on Monday, defeating 21-year-old American rookie Daniel Berger in a playoff to capture the storm-hit Honda Classic.

The 43-year-old Dubliner, a three-time major champion who has fallen to 297th in the world rankings, withstood a dramatic morning shootout for the $US1.098 million ($A1.40 million) top prize at the $6.1 million tournament.

Harrington found the water at the par-3 17th in regulation for a double bogey but sank a tension-packed 15-foot birdie putt at the par-5 18th hole to force the playoff, matching Berger on six-under 274 over 72 holes.

Both began the playoff with pars at 18 and then at 17, Harrington put his tee shot four feet from the cup and Berger found the water.

That allowed the Irishman to two-putt for the title.

Harrington won the 2007 and 2008 British Open and 2008 PGA Championship, the last of those being his most recent PGA victory.

Berger and Harrington were not the only leaders to stumble down the stretch, with England’s Ian Poulter and Paul Casey and American Patrick Reed also faltering over the final holes.

A major thunderstorm on Saturday pushed the finish to Monday morning, when sunny skies greeted players for a thilling back-nine title battle.