Rory McIlroy watches his drive from the 18th tee on the second day of the PGA Championship at Wentworth Golf Club

Virginia Water (United Kingdom) (AFP) - Rory McIlroy revived his hopes of victory in the European Tour’s flagship PGA Championship with a five-under par second round that left him four strokes off the lead as Ryan Gerard of the United States took the lead.

McIlroy had a poor finish to his first round at the Wentworth course, southwest of London, with three bogeys in his closing six holes.

But it was a different story on Friday for the Northern Irishman, one of just six men golfers to have won all four of golf’s major titles.

McIlroy, the reigning US Masters champion, made three birdies in his opening five holes.

The 37-year-old McIlroy is trying to reel in the injured Patrick Reed to win a record-equalling eighth Race to Dubai title – the competition which crowns the best player on the European Tour.

McIlroy dropped a shot on the par-four eighth to head into the turn on 33, but regained that stroke with a birdie from 16 feet on the 11th hole.

A birdie on the par-three 14th was followed by a bogey at 16.

McIlroy narrowly missed an eagle chance on the 17th but he tapped that in and then made another birdie on the last for a round of 67.

Reed retired midway through his second round with an injury, the American having been nine over.

“Unfortunately he’s pulled out this week, which gives me an opportunity to try to claw back some ground that I lost last week in Ireland,” said McIlroy, the world number two.

“This weekend is a big weekend for me to pick up a few points and make the race even tighter going into these last few weeks.”

Gerard, who had started the day at five under, rolled in a fine eagle from 20 feet on the 17th to take the outright lead, before finishing with a birdie in a superb round of 65.

Australia’s Adam Scott finished at 10 under after his 67 left him two shots off the lead and sharing second place with Italy’s Filippo Celli.

US PGA champion Aaron Rai, playing alongside McIlroy and British Open champion Ryan Fox in a showpiece group, also had a birdie-birdie finish for his 69, which leaves the Englishman at nine under alongside Spain’s Manuel Elvira.

New Zealand’s Fox was one of a quintet of players on eight under, with McIlroy, England’s Ross Fisher, Spain’s Ignacio Elvira and JJ Spaun of the United States.