DUBAI (REUTERS) - Defending champion Li Haotong fell foul of a new golf rule and incurred a costly two-stroke penalty on the final hole of the Omega Dubai Desert Classic on Sunday (Jan 27).

Caddies are no longer allowed to stand directly behind their player and help with alignment, a rule that was expected have more effect on women's golf, where it had become a common occurrence.

The new rule, one of a raft of changes introduced on Jan 1, states: "Once the player begins taking a stance for the stroke, and until the stroke is made, the player's caddie must not deliberately stand on or close to an extension of the line of play behind the ball for any reason."

Li had started to take his stance for a putt before his caddie, who had been standing behind him, moved to the side.

Though the caddie had moved away before Li completed his stance, European Tour officials still decided the Chinese player had breached the rule.

The penalty turned a birdie into a bogey at the par-five 18th and he recorded a 71 for the round.

Instead of finishing equal third at 16 under par, Li dropped into a tie for 12th.

The tournament was won by American Bryson DeChambeau, who fired a solid 64 to claim a seven-shot victory and his maiden European Tour title.

World No. 5 DeChambeau shot seven birdies and an eagle to blow away the competition, finishing at 24-under to set a tournament record at the Emirates Golf Club.

"Today I was happy with my game. I executed a lot of great shots," DeChambeau, who represented the US in last year's Ryder Cup, said. "Today was a pleasure. It was obviously a lot of fun to be able to finally hoist an international trophy, I'm so happy about that."

England's Matt Wallace finished second after twin birdies on the final two holes helped him sign off with a round of 68 to finish on 17-under 271 for the tournament.

Paul Waring (64), Ian Poulter (64), Sergio Garcia (66) and Alvaro Quiros (71) were in a four-way tie for third place on 272.