IRUMA, Saitama Pref. (Kyodo) Toshinori Muto fired an 8-under-par 64 to take a one-stroke lead after the opening round of the Diamond Cup on Thursday.
Muto, whose most recent victory came at The Championship by Lexus last November, rolled in 10 birdies against two bogeys at Sayama Golf Club.
South Korean Kim Kyung Tae shot a 65, while Taichi Teshima and Wayne Perske of Australia were a further two strokes back. Former U.S. PGA Tour player Shigeki Maruyama and Toru Taniguchi, winner of the Japan PGA Championship on May 16, carded 69s for 10th place.
Ryo Ishikawa, who missed the cut at the Japan PGA Championship for the third straight year, struggled to a 75 after some erratic shots with his driver.