Australian golfer Nick O’Hern shot three late birdies to grab a share of the third round lead at the US PGA Tour’s St Jude Classic in Memphis.

O’Hern birdied the 14th, 15th and 16th holes on his way to a three under par round to leave him at six under for the tournament along with Americans David Love III and John Merrick in the $US5.6 million tournament.

Just one shot behind the leaders on five under is a pack featuring Australia’s Robert Allenby and US Open champion Rory McIlroy.

Allenby fired a three under round while overnight leader McIlroy struggled with a two under par round.

The Northern Ireland star, ranked second in the world, led by a stroke when the day began after an impressive 65 on Friday but made six bogeys against four birdies in round three at TPC Southwind.

McIlroy is tuning up for his US Open defence next week at The Olympic Club.

McIlroy birdied the par four second but answered with a birdie at the next hole.

He made another bogey at the par four fifth but responded with a birdie at the par three eighth, only to take bogeys at the next two holes.

A birdie at the par four 12th was followed by bogeys at the par four 13th and par four 15th but a closing birdie helped lift McIlroy closer to the top.