Patrick Reed shook off a third-round rules controversy and held off Norway's Viktor Hovland over the back nine on Sunday to win the US PGA Farmers Insurance Open.

The 2018 Masters champion fired eight pars and a closing birdie on the back nine while rivals faltered to capture his ninth career US PGA victory, shooting a four-under par 68 for a five-stroke triumph -- the largest winning margin of his career.

"The biggest thing is I was mentally strong through the whole round," Reed said. "My wedge and my putter were working pretty well today and allowed me to have an easy stroll up 18."

World number 11 Reed finished 72 holes on 14-under 274 at Torrey Pines, where the US Open is set to be staged in June.

Sharing second on 279 were Hovland, Sweden's Henrik Norlander and Americans Tony Finau, Ryan Palmer and Xander Schauffele.

Reed was embroiled in a rules controversy Saturday over an embedded ball at the 10th hole where officials deemed he acted properly.

A similar call was made on an embedded ball situation Saturday involving Rory McIlroy at 18, with the PGA Tour saying Sunday that both players acted properly.

With memories of past rules issues adding to the cloud over Reed, he shook off critics to leave no doubt who was the week's superior golfer.

"My biggest takeaway is mentally I hung in there and stayed to the course," Reed said.

"I felt fine. I felt great throughout the day. I wouldn't have felt any other way. I was able to go out there and get the job done."

On Sunday, Reed called over a rules official regarding a ball that moved slightly on the par-3 16th green as he replaced it after marking. He was allowed to replace it where marked and two-putted from 14 feet for par.

Reed said he felt nerves during the round, not over the rules controversy but over swing tweaks that remain a work in progress.

"This is the first Sunday I had nerves going throughout the day with the swing. It's still not 100% where the swing needs to be," Reed said. "To not be 100% and still go out there and get the job done, it means a lot for me."

Reed became the first player to lead after the opening round and win the event since compatriot George Burns in 1987.

The 30-year-old American, who last won last February at the WGC Mexico Championship, has now won in four consecutive US PGA seasons.

Hovland, ranked 14th, was seeking a second victory in three starts, having taken the Mayakoba Classic in Mexico in December.

Reed clung to a one-stroke lead over Hovland until the par-4 14th, when the Norwegian sent his approach over the green out of bounds and made bogey to fall two back.

Reed found a bunker at 14, blasted out to seven feet and made his par putt to stay on 13-under. Hovland found the right rough off the 15th tee and made bogey then botched a two-foot tap-in to bogey the par-4 17th, leaving Reed ahead by four. Reed closed out the victory with an eight-foot birdie at the par-5 18th.

Hovland an early threat 

Reed began the day sharing the lead with Carlos Ortiz on 10-under par, but the Mexican stumbled to a 78. As rivals faltered, Reed seized command. Hovland made three birdies in four holes and briefly shared the early lead before Reed reached the green in two at the par-5 sixth and rolled in a 45-foot eagle putt, then holed a 25-foot birdie putt at the par-4 seventh to reach 13-under.

Reed stumbled with a bogey at the par-3 eighth, missing the green and a 13-foot par putt, but dropped his approach inside three feet at the par-5 ninth and tapped in for birdie to make the turn at 13-under, one ahead of Hovland.

South Korean Im sung-jae birdied five of the first eight holes to move within one of the lead, but began the back nine with three bogeys and a double bogey to fade.