Ben Curtis took over the halfway lead of the Valero Texas Open after Matt Every failed to cash in on his record-setting opening round.
Curtis made use of the calmer early conditions to return his second consecutive flawless five-under-par round of 67 to stand alone at the top of the leaderboard on 10 under.
David Mathis is his closest challenger two strokes behind, after he also shot 67 , while Every sat in a tie for third a shot further back after floundering in stormy conditions, dropping two shots before he was forced off after 16 holes.
After the wind and rain had delayed the round by two hours, darkness ended Every's round early with the American lining up an 11-foot putt for birdie at the 17th.
Every had set TPC San Antonio alight yesterday when he went around in a course-record 63, but four bogeys in his opening 12 holes today left him plummeting down the leaderboard.
The 28-year-old minimised the damage late with birdies at 14 and 16 to be level with Cameron Tringale, who carded an impressive second-round 65.
But it was Curtis who was deservedly out in front after he became just the fourth player on the PGA Tour this year to go bogey-free through the opening two days.
The 34-year-old American picked up four of his five birdies in his opening seven holes, after starting on the back nine, to go out in 32.
A steady run in saw him birdie only the par-three third, but it was enough leave him in the box seat to claim a first PGA Tour title in six years.
Curtis won the Open Championship in 2003 at Royal St George's, but he has been winless in America since the 2006 Lumber Classic.