Darren Clarke carded a superb opening 64 to lead after the first round of the Stg£1 million Dunlop Phoenix tournament in Miyazaki, Japan.
Clarke fired eight birdies and just one bogey for a two-shot advantage over England's Justin Rose and local duo Kaname Yokoo and Tsukasa Watanabe.
Rose carded five birdies and an eagle on the par-five 18th, but dropped shots at the 12th and 16th.
Spain's Sergio Garcia was a shot further back after a 67, but world number one Tiger Woods struggled to a level-par 71 in the wet conditions.
Clarke stormed to the turn in 30 with six birdies and after his only bogey of the day on the 16th, closed with two more birdies.
Defending champion David Duval ran up two bogeys and a double bogey but still managed a two-under 69 to lie five off the pace.