Australian Stuart Appleby could not complete his second round but remained atop the leaderboard at the rain-hit Houston Open.
With heavy rain delaying the start of play by almost three hours, the overnight leader was an error-free five under through 16 holes at the Redstone Golf Club when play was halted.
With two holes to complete on Saturday, Appleby was 11 under for the tournament, one shot clear of England's Greg Owen, who rocketed up the leaderboard after a course record seven-under 65.
Owen looked to be heading for a solid but unspectacular round until he birdied five of his final six holes to take the clubhouse lead with a midway total of 10-under 134.
"I felt like I hit a lot of good putts today," Owen told reporters. "The quality of putting is a lot better now. I'm not hitting so many pushed or pulled or short or anything. The quality is there.
"I don't feel like I've hit a bad putt today. They only just started falling towards the end. Hopefully, it will continue for the rest of the weekend."
After the morning rains had cleared, South Africa's Trevor Immelman was one of the first to make a move, spending most the day on top of the leaderboard following a five-under 67.
Mixing six birdies with a single bogey, the South African posted an aggregate score of eight-under 136 to move into contention for his first PGA Tour win.
"It's always been a dream of mine to play the PGA Tour," said Immelman, who has split his time between the European and US Tour in the past. "I really enjoyed my time playing in Europe, but for me, my goal was always to try and get over here.
"So once I had the opportunity, I really wanted to give it my best shot and see what I could do. I'd love to win, there's no doubt about it, and I'm hoping that I'm going to win and win many times and win big tournaments."
Australia's Aaron Baddeley, riding the momentum from his maiden PGA Tour win last week at the Heritage Classic in South Carolina, followed an opening 68 with a two-under 70 to sit just five shots off the lead.
Defending champion Vijay Singh, who is chasing a third consecutive Houston crown, had a tough start and even rougher finish to his round of one-under 71.
The world number three opened with a bogey at the first but recovered with a birdie at the second before a double-bogey at the fifth left him one over for the round.
Singh looked to have put his stuttering start behind him when he reeled off consecutive birdies at six, seven and eight and added two more at 13 and 15. The Fijian's hard work, however, was undone by a bogey-bogey finish that left him at four-under 140 heading into the weekend.
John Daly, who lost the Houston title to Singh at the first playoff hole last year, also had rollercoaster afternoon before finishing with a level-par 72.
Playing the back nine first, Daly got his round off to stumbling start, mixing a pair of double-bogeys and two bogeys with a single birdie on his outward nine. The former British Open champion rallied in style, however, carding five birdies on his back nine, including one at the last, to get back to level par and three-under 141 for the tournament.
Padraig Harrington was right on the cut mark of level after adding a 73 to his opening 71, as was Graeme McDowell, who shot a pair of 72s.
