Los Angeles - Britain's Justin Rose fired a six-under par 64 on Friday to grab the second-round lead at the US PGA Fort Worth Invitational, boosting his confidence for next month's US Open.
The 37-year-old Englishman, who won his lone major title at the 2013 US Open, stood on 10-under par 130 after 36 holes at Colonial Country Club.
He had a one-shot lead over Argentina's Emiliano Grillo, who carded a three-under par 67 for 131 as changing wind and swiftly falling temperatures made for tougher scoring conditions in the afternoon.
"The way I played through the first 15 holes today was about as good as I've played in a long time," Rose said.
Rose, whose most recent win came at last December's Indonesian Masters, also won last year at Shanghai and Turkey and took gold at the 2016 Rio Olympics since last winning on US soil at New Orleans in 2015.
Rose, seeking his 22nd career title and ninth overall on the US PGA circuit, began on the back nine and birdied three consecutive holes, sandwiching nine-foot birdie putts at 14 and the par-three 16th around a two-footer at 15.
He opened his second nine with back-to-back birdies, then made his longest putts of the day for birdies from 35 feet at the sixth and 16 feet at the seventh.
"I did a lot of good things," Rose said. "The end of my round got a little scrappy but until the last three holes it was pretty flawless. I hit every fairway pretty much and I hit every green out there up until that point.
"I left a few out there on the greens early but I didn't get frustrated. I made a little nine-footer on my fifth hole of the day which kind of took the lid off it and from there got into a nice rhythm really."
Rose, last year's Masters runner-up to Sergio Garcia, faces his next major challenge in the US Open on the links layout at Shinnecock next month.
"All aspects of my game are showing signs," Rose said.
Grillo teed off on 10 and birdied three of his first four holes. He rolled in a 28-foot birdie putt at the 17th and dropped a 33-footer for birdie at the par-three fourth.
But his bid to run down Rose faltered with back-to-back bogeys at 18 and one, and he dropped a shot at the third as well.
US Open champion Brooks Koepka played early and climbed the leaderboard with a seven-under par 63 that propelled him into a tie for third on 133. He was level with Japan's Satoshi Kodaira, who had five birdies in his three-under 67.
Koepka, playing his fourth tournament since missing more than three months with a wrist injury teed off on 10 and picked up five of his eight birdies in his first nine holes.
Koepka, who was three-over through 13 holes on Thursday has made 11 birdies over his next 23 holes.
"I don't care how many over or how many under I am," he said. "I'm still going to fight through it."
Leading second-round scores on Friday in the US PGA Tour Fort Worth Invitational in Fort Worth, Texas (USA unless noted, par-70):
130 - Justin Rose (ENG) 66-64
131 - Emiliano Grillo (ARG) 64-67
133 - Satoshi Kodaira (JPN) 66-67, Brooks Koepka 70-63
134 - Tyrone Van Aswegen (RSA) 67-67
135 - Tom Hoge 69-66, Alex Cejka (GER) 66-69, Kevin Na 62-73, Ben Crane 66-69, Beau Hossler 64-71, Ben Silverman (CAN) 66-69, Harris English 68-67, Kevin Tway 66-69, Bryson DeChambeau 68-67
136 - Tim Herron 66-70, Kevin Streelman 69-67, Jason Kokrak 69-67, Ryan Armour 68-68, Tom Lovelady 67-69, Rickie Fowler 67-69, Charley Hoffman 63-73, Andrew Putnam 64-72