HONG KONG - Spain's Javier Colomo, ranked outside the world's top 500, upstaged Rory McIlroy and compatriot Miguel Angel Jimenez to grab the first-round lead at the UBS Hong Kong Open on Thursday.

The unheralded Colomo, languishing at 507th in the world, fired six birdies in a flawless six-under-par 64 to take a shock lead at the $2 million showpiece that is co-sanctioned by the European Tour and the Asian Tour. His sizzling round was in stark contrast to that of McIlroy's. The defending champion endured a torrid day at an increasingly blustery Hong Kong Golf Club, carding a three-over-par 73 to leave him well off the pace.

The veteran Jimenez, 48, who is bidding to become the European Tour's oldest winner, was tied in second with Australia's Andrew Dodt, a shot behind Colomo. Jose Maria Olazabal was among five players in tied fourth after matching 66s. "I probably just lacked a bit of energy out there. I felt a bit lethargic -- mentally, more than physically, if I am being honest," said McIlroy, 23. "I started off OK and just got more and more frustrated as the round went on. I just felt like I was hitting some decent shots and just not really converting any chances for birdies and I just let it get to me a little bit." The Northern Ireland star has enjoyed a hugely successful year, his third place at the Barclays Singapore Open last weekend meaning he has topped the money charts in the United States and Europe.

"I suppose after last week, it was always going to be a bit of a let-down," he added. "I feel like I'm playing well enough. I just need the head and the golf to match up and I'll be OK. Hopefully I'll go out there tomorrow morning and see if I can muster something a bit better." Colomo, who plays on the Asian Tour, where he sits a modest 33rd on the money list, said: "I'm playing really good because this is my first season here (in Asia). The first six months it was very hard for me and my wife."

"But now we are more comfortable and more happy, perfect," added Colomo, 28, who has failed to come through the European Tour qualifying school on three occasions, leaving him to pursue his career in Asia. He said: "I'm only here with my wife. I'd like some family to come here to watch me play, but it is very expensive at the moment. We don't know what will happen in the future."

Jimenez set the early pace with his 65 that was studded with seven birdies. Under warm and sunny conditions in the morning, he was set for an even better start to a tournament he has won twice before, but two bogeys on the last two holes took the gloss off his otherwise faultless performance.

"I played very solid all day long," said Jimenez, who was a vice-captain of Europe's triumphant Ryder Cup team. "The finish was the only thing not very nice. I like the golf course. I first won here in 2004 and then in 2007. It's an old-fashioned golf course and I like it here very much." Des Smyth currently holds the record for the oldest victory on the European Tour, courtesy of his win at the Madeira Islands Open aged 48 years and 34 days.

Spain's Olazabal, Europe's victorious Ryder Cup captain, sat alongside China's Zhang Lianwei, Fredrik Andersson Hed of Sweden, Y.E. Yang and Italy's Lorenzo Gagli at four under. Matteo Manassero, the 19-year-old who won the Singapore Open, was a shot further back in tied ninth.