Los Angeles - New Zealand's Danny Lee and red-hot Kevin Kisner were in a four-way tie for the lead halfway through the PGA Tour's Colonial as an already crowded leaderboard got more congested on Friday.
Lee fired a six-under 64 and American Kisner shot his second straight 67 to move into a tie with Webb Simpson (66) and Scott Piercy (66) for a one-shot lead at six-under 134.
But there is no time to relax as a strong field that includes several major winners is nipping at their heels.
Windy conditions helped create the logjam at the top with 21 players within five shots of the leaders after the first two rounds at the Colonial Country Club course in Fort Worth, Texas.
Reigning Masters champion Sergio Garcia (66) and two-time major winner and defending champ Jordan Spieth (68) are within striking distance heading into the weekend.
Garcia and fellow Spaniard Jon Rahm (69), England's Paul Casey (66) and American Sean O'Hair (68) are tied for fifth at five under 135.
Northern Ireland's Graeme McDowell is alone in ninth, two shots adrift. Tony Finau shot a 65 and climbed into contention and into 10th place.
First-round co-leader Kelly Kraft stumbled to a 73 and is tied for 12th in a pack of nine golfers that includes Spieth, Stewart Cink (70) and Kevin Tway (70), all four strokes back.
Lee's round featured seven birdies and a bogey and was the low round of the day.
"I was hitting the ball very nicely today," said Lee, a Kiwi from Rotorua on the North Island. "I had strong finish, and that's what I need to have carrying over the next couple days."
Kisner continued his superb play this season as his round included four birdies and a bogey on No. 17.
Kisner's only PGA Tour victory came by an impressive six shots in 2015, but he has been knocking on the door with six runner-up finishes in his career, including the 2017 Arnold Palmer Invitational.
Kisner said the key for him is to simply put his head down and not come up for air until Sunday.
"I only had one bogey each day and I played nicely coming down the fairway," Kisner said. "I probably got the better part of the draw with the weather with the wind laying down this afternoon. We got to keep making birdies and we'll look up on Sunday and see if we have a chance."
Spieth, who started on the back nine, began with bogeys on three of his first five holes but turned it around with a birdie on the par-four 15th. He added four more birdies on the front nine and parred his final four holes.
"That's what we needed to see," said the Texas native Spieth. "I hit the fairways, and if I missed the fairways they were good drives that were just off that gave me an opportunity to be on the green.
"I'm playing well. I'm just either not catching the breaks or my short game is just a little off."
Garcia, who earned his first USPGA Tour title at the Colonial in 2001, followed up a one-under 69 on Thursday with a second round four-under in his eighth career start at the event.
134 - Webb Simpson 68-66, Kevin Kisner 67-67, Danny Lee (NZL) 70-64, Scott Piercy 68-66
135 - Paul Casey (ENG) 69-66, Sergio Garcia (ESP) 69-66, Jon Rahm (ESP) 66-69, Sean O'Hair 67-68
136 - Graeme McDowell (NIR) 66-70
137 - Tony Finau 72-65