J.J Spaun changed his putter and immediately found himself in contention. The reigning US Open champion believes he's getting lined up just about right three weeks before he tries to defend his first major title.

Spaun surged with four birdies on his front nine before a couple of late bogeys in a two-under 68, which put him at eight-under on Friday, two shots behind Englishman Jordan Smith and one back of Hideki Matsuyama and three others after 36 holes.

Smith took the lead by himself with a 31-foot birdie putt at the par-3 16th, saved par from a bunker on 17 and missed a nine-footer for birdie on 18 to finish at 10-under with a second consecutive 65.

"It's going to be a new experience for us out here leading for the first time," said Smith, a 33-year-old PGA Tour rookie who qualified through the DP World Tour and had his best finish at third in the Valpar Championship.

"Not going to force anything, not going to rush anything, just going to see what happens and enjoy it."

Matsuyama, the 2021 Masters champion with 10 other tour victories, and Michael Thorbjornsen had matching 65s. They were at nine-under with Ryan Gerard (67) and 2023 British Open champion Brian Harman (66).

Spaun was joined by Akshay Bhatia (65), Russell Henley (66), Brice Garnett (66) and Alex Smalley (67).

A.J Ewart had the second hole in one in two days at the 195-yard, par-3 16th - Brandt Snedeker aced it in the opening round - and followed an opening 70 with a career-best 63; the low round of the day. He was at seven-under with Michael Brennan (66) and Mackenzie Hughes (67).

Gary Woodland, the 2019 US Open champion, was among 11 players at six-under at Hogan's Alley, where light winds and still-soft conditions led to 154 sub-par scores through two rounds.

Defending champion Ben Griffin shot a second consecutive 68 and was four-under along with Justin Thomas, a stroke above the cut line.

Spaun, who was among six players tied for the lead after an opening 64, missed the cut in six of his first 13 events this year, including the Masters and PGA Championship. He said he changed putters because he was losing confidence on the greens.

The highest-ranked player in the field at No.9, Spaun kept his hot front nine going with a 15-foot par putt at 17 and was still without a bogey for the tournament before missing a pair of par putts outside 15 feet on the seventh and eight holes.

"It's nice to see that the putter switch was a good change," Spaun said. "I found myself kind of resenting my putter at times when I'm out on the course.  The weeks that I putt just slightly better than average, I contend."

Australians Cam Davis (72, 68) at even par and Karl Vilips (79, 69) at eight-over missed the cut.