Hideki Matsuyama shot a second straight 65 to take a one-shot lead halfway through the PGA Tour's season-opening tournament in Hawaii.
The former Masters champion carded eight birdies as he reached 36 holes at The Sentry with just one bogey on his card.
His 16-under-par total at Kapalua leaves him just one ahead of fellow major champion Collin Morikawa, who rattled off five straight birdies in his 65 from the 13th.
England's Harry Hall birdied four of his final five holes en route to a 65 that moved him into a 13-under-par group that also included US Ryder Cup captain Keegan Bradley and Wyndham Clark, who both carded 64s.
England's Harry Hall enjoyed a positive second round by three shots off the lead
Maverick McNealy, who tied the lowest round of the day with a 64, and overnight leader Tom Hoge are among those trailing Morikawa, along with Canada's Corey Conners after a second consecutive 66 and Belgium's Thomas Detry.
“I have two jobs,” Bradley said. “My one job is here and my other job is to be the captain and leader of the US Ryder Cup team.
“I'm really enjoying being captain – and I love playing golf. So it's not hard stuff. It's stressful, sure, but I'm enjoying both.”
Scotland's Robert MacIntyre shot a second-round 66 to move to 10 under, two clear of England's Matt Fitzpatrick after a 65.
“I'm definitely happy with where I'm at,” Matsuyama said. “Obviously the views here are beautiful.
“I haven't played well here for a while, so it's good to start well here.”
Watch round three of The Sentry, live Sky Sports Golf from 18:00 on Saturday or stream from NOW.
Get the best prices and book a round at one of 1,700 courses across the UK and Ireland