HONOLULU — Cameron Smith of Australia won his second PGA TOUR title on Sunday when he least expected it.

Two shots behind with two holes to play, Smith made an 8-foot birdie putt on the final hole to force a playoff against a faltering Brendan Steele, and won the Sony Open in Hawaii with a two-putt par from 10 feet on the first extra hole.

Steele had a three-shot lead when he holed a bunker shot for birdie on the 11th hole and he never trailed the entire day until it fell apart at the end. He missed a 6-foot par putt on the 17th, and then hit a wild hook from the fairway on the par-5 18th and never had a reasonable look at birdie.

On the 10th hole for the playoff, Steele was in ideal position in the fairway, 88 yards from the hole, when he hit wedge over the green. He chipped off the rain-soaked grass to 15 feet and missed the par putt. Smith, who had driven into right rough, chased his shot to 10 feet.

It was only easy at the end for Smith, who shared the team title with Jonas Blixt in the PGA TOUR’s Zurich Classic three years ago.

“Just had to hang in there. No one was playing good golf today, it seemed like,” Smith said after a 68. “Just hung in there, and what do you know?”

Steele was trying to win for the first time in just over two years. This was hard to take.

“Everything that could go wrong went wrong today,” Steele said. He closed with a 71.

A final round that was wet, and gray came to life in the final hour.

Steele brought possibilities into play when he missed the green to the left on the par-3 17th, pitched to 6 feet and missed his par putt, reducing his lead to a single shot.

Ryan Palmer and Webb Simpson were in the group ahead, both one shot behind. From a fairway bunker, Palmer went with fairway metal and sent it soaring so far to the right that it bounced off the metal railing atop a monster video board, beyond the corporate tent and vanished, presumably in a backyard. He had to return to the bunker and made bogey.

Simpson’s wedge skipped off the soaked green and settled 15 feet behind the hole. He narrowly missed the birdie putt, shot 67 and finished alone in third.

Steele went just as far offline as Palmer, just the opposite direction. It bounced off the roof of the tents left of the green and stopped near the ropes lining the 10th fairway. Given free relief from the grandstands, he hit wedge to 30 feet and two-putted for par.

Smith holed his 8-footer for birdie for the second playoff in two weeks. They finished at 11-under 269.

With his bogey on the 18th, Palmer had to settle for a 68 and tied for fourth with Graeme McDowell, who had a 64 to match the low score Sunday, and Kevin Kisner, who played in the final group but made only one birdie on the back for a 69.

Lanto Griffin extended his steady play. The Houston Open champion, who opened with a 71 and was in danger of missing the cut, closed with a 64 to tie for seventh. In his 10 starts this season he has finished in the top 20 eight times.