Tim Herron shares third place with Charles Howell III at 15 under par. Herron carded a 10-under 62, while Howell posted a 7-under 65. Craig Barlow (67), Steve Lowery (64) and John Senden (67) are tied for fifth place at 14 under par.
Players are rotating over three courses over for the first three rounds including the TPC at Summerlin and Southern Highlands Golf Club, which are both par-72s, as well as the par-71 TPC at The Canyons.
Flesch, who shared the overnight lead with Stuart Appleby, opened on the front nine at the TPC at The Canyons. He burst out of the gate with a birdie on the first and came back with an eagle on the par-5 fourth.
He stumbled to a bogey on the par-3 seventh to make the turn at 12 under. But he caught fire around the turn.
Flesch converted back-to-back birdies from the 10th, but faltered to a bogey on the par-3 12th. He came right back with a birdie on No. 13 and made it two in a row when he birdie the 14th.
He capped a run of three straight birdies on the 15th and closed his round of 7-under 64 with a birdie on the par-4 17th.
'I made a lot of putts on the back side and capitalized on my chances,' Flesch said.
Verplank torched the TPC at Summerlin for a 10-under round of 62. He opened on the 10th tee with a pair of pars. He then drained back-to-back birdies from the 12th to get to minus-9.
Verplank, a four-time winner on tour, birdied the 15th and 16th. He came back with a birdie on No. 17 and made it four straight by closing out his opening nine with a birdie on the 18th.
He also birdied the first to make it five in a row. He climbed to 15 under with a birdie on the par-5 third.
With that birdie, Verplank was 8 under through 12 holes and looking at a legitimate shot at shooting 59. However, he could only manage birdies on Nos. 6 and 9 coming in to grab a share of the lead.
'I haven't played well since the U.S. Open,' said Verplank, whose last win came at the 2001 Bell Canadian Open. 'I've been beating myself up enough and this week I decided to just go out and play.'
Bob Burns and Russ Cochran posted matching rounds of 5-under 67 to move to 13-under-par 131. They share eighth place with Rory Sabbatini (64), Stuart Appleby (68), Woody Austin (65), Aaron Barber (67), Rich Beem (67) and Dean Wilson (63), who all stand at 13-under-par 131.
Jim Furyk, a three-time winner of this event, posted a 5-under 67. He is in a tie for 24th place at 11-under-par 132.
This five-round event will have its' cut after Friday's third round.