Bad weather frustrated Ernie Els in his bid to win two PGA Tour events in a row as he led by two shots at the Arnold Palmer Invitational.

Els, competing for the first time since his win at Doral, was 11 under par, two clear of American Kevin Na.

Na was alone in second a shot in front of Els' fellow South African Retief Goosen, Ben Curtis and Chris Couch who were all on eight under.

The 'Big Easy' resumed on Sunday morning with a shot ahead of Curtis - who slipped up with two late bogeys in Saturday's third round - and Els was round the front nine with a two-under 34 featuring four birdies and a pair of bogeys.

Birdies at the 10th and 12th followed before a double bogey on the 13th, then another dropped shot on the next, slowed his victory march.

That sticky run was halted before he moved on to the 15th, with a reprieve brought about by the impending storms as heavy rain arrived and threatened to scupper play for the day.

Na, meanwhile, was showing the form which earned him rounds of 68 and 70 on Thursday and Friday before Saturday's 72. Two birdies and a bogey saw him complete the front nine in 35 and he picked up shots on the 11th and 12th before the horn prevented he and Els teeing off at the 15th.

Italian Edoardo Molinari was seven under, also after 14 holes, with Englishman Brian Davis tied for 24th after a 70 on Sunday saw him finish on par.