Xander Schauffele fired a 63 to move top of the leaderboard at Tokyo 2020, while home favourite Hideki Matsuyama and Rory McIlroy made big moves on Friday.
The threat of serious weather caused another delay on day two, and eventually brought an early end to play with Matsuyama among those not to finish his round.
But Schauffele, who has a big support in Japan as his mother was brought up in the country, sat pretty at 11 under as the stellar names bared their teeth at Kasumigaseki Country Club.
SCHAUFFELE SHUFFLES UP TO TOP SPOT
Sepp Straka was the overnight leader of a very unusual looking leaderboard after the first 18 holes but a level-par 71 means he is now three shots back.
Instead it is Schauffele, a perennial nearly man in the majors, who leads the charge for gold at the halfway stage.
The world number five had two bogeys on his card but also had a pair of eagles to go with six birdies in a sublime round.
Mexico's Carlos Ortiz is only a shot further back after a four-under 67.
HOME HOPE HIDEKI ON THE MOVE, MCILROY IN CONTENTION
Matsuyama was among the pre-tournament favourites in Tokyo, a status enhanced after making a major breakthrough at the Masters in April.
After starting with an opening 69, Matsuyama was six under through 16 holes of his second round and eight under overall for the tournament.
McIlroy matched Matsuyama's round-one score but shot five under in round two and is well in the mix four shots back.
Shane Lowry, the 2019 Open champion, and Paul Casey are also at seven under with McIlroy.
Champion Golfer of the Year Collin Morikawa and Patrick Reed have work to do at three under, while Justin Thomas is one under for the tournament with a hole to play in his second round.