Jason Knutzon of the United States fired a 7-under 64 to take a two-stroke lead after the first round of the Panasonic Open on Thursday.
Knutzon offset a lone bogey on the par-4 17th with seven birdies at the Chiba Country Club to finish two strokes ahead of Thailand's Udorn Duangdecha and Satoshi Kodaira of Japan.
Kim Hyung-sung of South Korea shot 67 and was tied for fourth with compatriot Hur In-hoi, Hiroshi Iwata of Japan and Thailand's Panuphol Pittayarat.
Defending champion Yuta Ikeda got off to a shaky start with back-to-back bogeys on Nos. 2 and 3 and finished at 2-over 73.
The tournament is co-sanctioned by the Asian Tour and Japan Golf Tour Organization.