Jason Day continued his golden run with the putter to lead a strong Australian contingent at the halfway stage of the Byron Nelson Championship in Texas.
The 22-year-old, who has battled several health issues this year, followed his opening 66 with a second-round 65 to lie just one stroke behind Americans Cameron Beckman and Blake Adams at nine-under.
Beckman, 40, already a winner this year on the PGA Tour at the Mayakoba Classic in Mexico but with six missed cuts in seven starts since, fired a nine-birdie, no-bogey round to tie the course record of 61 at the par-70 TPC Four Seasons Resort Los Colinas near Dallas and move to 10-under after 36 holes.
Beckman had been early at the course on Friday morning to complete his first round due to a three-and-a-half hour weather delay on Thursday and having finished on a high with two birdies from his final three holes for a 69, he continued his good momentum with early birdies in his second round.
"I made a couple of nice putts on 16 and 18 to get to one-under for the tournament and birdied 10 and 11 out of the box," Beckman said. "And I've been hitting the ball good the first day, and it continued all day today."
"I didn't know you could shoot 61 on this golf course to be honest with you, but obviously I did and I'm thrilled to death."
"Getting up at four in the morning is not great, but I carried that confidence and even though I was one over, I knew I was playing better than that, and getting off to a good start to the second round was huge, and I just had a nice flow all day."
"I hit a lot of greens and putted great and just real comfortable off the tee, and hopefully it can continue for the weekend."
Beckman shares the 36-hole lead with American Blake Adams, one of seven first-round leaders, who followed his 66 with a bogey-free 64.
They are one clear of Day with another Australian, veteran Steve Elkington, and American Jeff Overton on eight-under-par.
Elkington, 47, had completed an opening 66 for part of that shared 18-hole lead and the 1995 US PGA champion, without a tournament victory since 1999, went straight back out and shot another 66, recovered from back-to-back bogeys on his back nine, having started at the 10th.
Day was the best of the later starters, after kick-starting his second round with an eagle three at the seventh and a birdie at the par-four 10th.
"It's exciting," Day said of being in contention. "I haven't played as well as I would have liked to this year, and my main goal tomorrow is to stay patient and just try and get myself into some good opportunities."
American Jay Williamson and Australian Marc Leishman, last year's PGA Tour rookie of the year, both carded consecutive 67s to get to six-under while there was also a 64 from Ben Crane, a 65 from Robert Garrigus and a 66 by DA Points to reach the same mark.
US Ryder Cup captain Corey Pavin showed he is still competitive as a player as he posted a 67 to get into a group on five-under.
Aussies Jarrod Lyle and Mathew Goggin are a further shot back at four-under with Rod Pampling, Nathan Green and James Nitties among a large