Beau Hossler of the United States carded a 5-under 65 to take a one-shot lead midway through the Zozo Championship, Japan's only PGA Tour event, on Friday.
Hossler had seven birdies and two bogeys in the second round, moving to 7-under for the tournament at Narashino Country Club in Inzai, Chiba Prefecture.
The 28-year-old has recorded four top-10 finishes in the 2022-23 season and is looking for his first career win on the tour.
Compatriot Justin Suh posted a 66 to sit one stroke off the lead.
Japan's Satoshi Kodaira, a U.S. PGA regular, was a further shot behind after a 68.
First-round leader Collin Morikawa, a two-time major champion, struggled to a 73 and a share of eighth place at 3-under. Host country favorite Hideki Matsuyama was even worse, with his 76 dropping him into a tie for 61st at 5-over.
The winner of the no-cut event will receive $1.53 million of the $8.5 million purse.