Rory McIlroy challenge falters at Riviera

The world number three made a stunning start to his final round, eagling the first to jump into a share of the lead but from there his round unravelled.

The 26-year-old, making his first start of the year in America, dropped shots at the fourth, sixth and seventh to reach the turn in one over par 35.

Suddenly five shots behind after nine holes, things failed to improve for the Holywood golfer who dropped further shots at the 11th, 12th, 13th and 16th.

He completed his round with birdie at the par four 18th, signing for a four over 75 that left him in a share of 20th.

Padraig Harrington also struggled and signed for a four over 75 that saw him finish tied for 45th.

American Bubba Watson grabbed his ninth tour title carding a 68 to top the leaderboard, one shot ahead of Adam Scott and Jason Kokrak.