"I played really well, I haven't played like that lately," O'Malley told reporters.
"I drove the ball well, I hit every fairway, I can't really fault anything today."
After picking up four birdies and a bogey in his first nine holes, O'Malley took the lead in style, sinking a 45-foot putt on the par-four sixth, his 15th hole, giving him an early chance of clinching his first European Tour win in seven years.
Stenson, world number 13, got off to a flying start with four birdies in his first seven holes, and finished strongly with a birdie on his last hole after two mid-round bogeys.
|"I drove the ball well, I hit every fairway, I can't really fault anything today."|
The Swede, currently second on the European order of merit, will be keen to make amends after losing to Spain's Gonzalo Fernandez-Castano in a play-off at this tournament two years ago.
"Obviously you don't want to bring back the memories of how it felt five minutes after losing a play-off, but I enjoy myself here," Stenson said.
Putting saves Singh
Singh, 2006 Asian order of merit champion, said his putter made up for a few wayward tee-shots in a five-birdie round only marred by a dropped shot on the sixth, his 15th hole.
"I would prefer good putting to good ball striking any day," Singh told reporters at the $2.3 million European and Asian Tour co-sanctioned event.
Australia's Scott Hend, who in the morning raced into first place with an eagle on the par-five second, now trails the leaders by two strokes after a disappointing double bogey towards the end of the round to card a three-under 69.
Michael Campbell, 2005 US Open champion of New Zealand, and Australia's Greg Norman are among a clutch of players four strokes off the pace after posting one-under 71s.
Norman, making a rare European Tour performance, was unhappy with a mix of three birdies and two bogies.
"There was a bit of rust in concentration, two bad club selections, which you should never do," Norman said.
Retief Goosen, two-time US Open champion, overcame a horror start to finish five off the pace on even par, holing four birdies to cancel out four bogies in his first seven holes.