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 McIlro’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,” he added.
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.