Hideki Matsuyama has hit the front at the halfway mark of the Zozo Championship on home soil, holding a one-shot lead from Cameron Tringale.
The 2021 Masters champion, who had been second following the opening day, carded a two-under-par 68 on the second round to claim the lead at eight under after 36 holes.
Opening-round leader Hiroshi Iwata struggled with a three-over-par 73 to slip four shots off the pace.
Matsuyama had three birdies and one bogey for his round in cold and rainy conditions in Chiba.
Tringale moved up the leaderboard with a four-under 66 that included five birdies, finishing by sinking a long putt to be within one shot of Matsuyama.
Englishman Matt Wallace birdied his final three holes to be two shots behind the Japanese leader and level with Brendan Steele at six under after 36 holes.
Tommy Fleetwood is five under, with Sebastian Munoz equaling Tringale's round to be four under after two days alongside a group of five other players including Iwata.
Open champion Collin Morikawa is seven strokes behind after a two-under 68, while Tokyo Olympic gold medalist Xander Schauffele struggled with a round of 74 to be 12 shots back.
Leaderboard at the halfway mark of @ZOZOCHAMP :— PGA TOUR (@PGATOUR) October 22, 2021
1. Hideki Matsuyama (-8)
2. @CamTringale (-7)
T3. @MattSJWallace (-6)
T5. @JoacoNiemann (-5)
T7. Six players tied (-4)