Rory McIlroy shot 64 but could not keep an unwell Mike Lorenzo-Vera off top spot as the Frenchman carded the lowest opening round in the history of the DP World Tour Championship, Dubai.
World number two McIlroy, a two-time champion at Jumeirah Golf Estates, closed Thursday's play one stroke behind Lorenzo-Vera.
The pair turned in well-matched scorecards, each showing an eagle and a solitary dropped shot, but the four-time major winner sunk one birdie fewer than his rival.
With former rugby player Niall O'Connor acting as his caddie, McIlroy went out in 31 but saved the best until last.
On the 18th hole, he nailed a stunning approach to within three feet and holed the subsequent eagle putt to conclude an excellent round.
Still it was shy of Lorenzo-Vera's effort, the world number 96 overcoming illness to earn himself a slice of history with an unmatched opening 18 holes to sit nine under.
"Honestly, I'm not feeling well at all," said Lorenzo-Vera, who has never won on the European Tour. "I have no energy. I had a big lung infection in South Africa and a big treatment and really feel bad on top of that.
"I felt that if I really relaxed a lot, just swing it like 70 per cent or maybe less, the ball was still flying pretty well. Try to be pretty clever and not too aggressive and then the putter got hot. So that worked."
Race to Dubai leader Bernd Wiesberger went round in 70 and is still projected to take the top prize based on day-one standings.
His closest rival for that honour at the start of the week, Tommy Fleetwood, dropped a couple of shots on the back nine to sign for a five-under-par 67.
Of the three other names in with a chance, Jon Rahm fared best as he got to six under, but Matt Fitzpatrick's 71 and The Open champion Shane Lowry's 73 are likely to have ended their hopes.