Ireland's Shane Lowry acknowledges the crowd after getting a birdie on the 9th hole during the third round of the British Open Golf Championships at Royal Portrush in Northern Ireland on Saturday. Photo: Peter Morrison/AP

PORTRUSH  Ireland's Shane Lowry forged into the lead at the British Open as he moved to 13 under with six holes of his third round remaining on a becalmed Dunluce links on Saturday.

With England's Tommy Fleetwood nipping at his heels, an inspired Lowry claimed his fifth birdie of the day at the par-five 12th to move a stroke clear to the delight of the galleries who were roaring him on across the course.

Fleetwood, playing in the match ahead with Lee Westwood, was also five under for the day having started a shot behind Lowry and American JB Holmes.

Westwood had earlier briefly gone to the top of the leaderboard after a run of three successive birdies but dropped back to nine under with a bogey at the 10th after driving into a bush.

Holmes was tucked in on 11 under.

England's Justin Rose was playing himself into contention on a day of red numbers on the board. He had moved to 10 under with three holes remaining.

Danny Willett had taken the clubhouse lead with a sizzling six-under 65 to reach seven under, before American Rickie Fowler, still awaiting his first major after knocking on the door so many times, moved to eight under with a 66.

Willett, winner of the Masters in 2016, missed a birdie putt on the 18th that would have set a new course record as the calm weather conditions produced a birdie feast.

World number one Brooks Koepka, playing with Rose, was two under for the day, six shots off the lead, with three holes remaining but was struggling to mount a charge.

Defending champion Francesco Molinari's hopes of retaining the title look over after he could only manage a one-over 72 to leave himself two over going into the final day.