Wagner chipped in for birdie on No. 8 to start his climb from a three-shot deficit. He also rolled in a 30-foot birdie putt on No. 12. His best work before the third round was stopped by wet conditions, however, were the par saves.
''I was hanging on, hitting little quack hooks to the green but just somehow getting it up and down and making par putts, and really just trying to survive and make as many pars as I could.''
He was at 15 under par and facing a short iron into the par-5 16th when a sponge roller couldn't keep water off the front of the green, from where Scott Piercy was trying to play.
Piercy, who had been in the lead since his opening 62 that set the course record at Silverado, was at 14 under. Also at 14 under was Patton Kizzire, who was facing a 20-foot birdie putt on the 17th green.
The dark clouds drooping over the foothills in Napa Valley were the first signs of the peculiar day.
Paul Casey, who was two shots behind when play was halted, was making up ground on Piercy on the front nine until his tee shot clipped a tree, ricocheted somewhere and was never found. Fans indicated that it shot across the fairway and went out of bounds into some trees, but that wasn't his golf ball. Either way, the lost ball cost him two shots.
Piercy, who started the third round with a three-shot lead, hit a tee shot that was stymied by a tree, and when he walked up to play his third shot, another tree trunk blocked his path. He played back to the fairway and hit a superb pitch-and-run to 2 feet to limit the damage to a bogey.
The real pain was later.
Piercy missed a 6-foot birdie putt that was downhill with a wicked right-to-left break. He took a step toward the hole on the ninth for his birdie putt only to stop in his tracks when it spun around and out of the cup. He missed a 4-foot birdie putt on No. 10. And then on the par-3 11th, he watched his tee shot hit the base of the pin and carom off the green.
Through all his travails, he still was only one shot behind.
''I had a ball fly in the hole, I had a couple balls lip out,'' Piercy said. ''Just maybe a little off today as far as the scoring. But I gave myself lots of chances , and even though I didn't score well, I'm one back. I'm in a good spot.''
The third round was to resume Sunday morning, and starting times for the final round already had been moved up because of more rain forecast for the afternoon.
Martin Laird was 12 under through 16 holes. The best 54-hole scores posted belonged to Michael Kim (65) and Brendan Steele (67), who were at 11-under 205. Phil Mickelson hit a wild tee shot in the rain and made bogey on the par-5 closing hole for a third straight 69. He was six behind.
No person was more responsible for the PGA Tour's season-opening event having a decent chance to finish than JT Poston. In his first PGA Tour event, he holed an 8-foot birdie putt on his final hole for a 69 that moved the cut line to 3-under 141.
That meant 70 players made the cut. His birdie knocked out 16 players.
Piercy finished the second round Saturday morning with a 67 for a three-shot lead over Casey and Wagner.
Casey had another lost ball late in the second round, but this turned out much better. He was about 30 seconds away from abandoning the search when a spectator held up a ball with the Nike swoosh and a blue pen dot and said, ''Is this it?'' The spectator had found it in the hazard, so while Casey still had a one-shot penalty, he was able to drop away from the grandstands and save par for a 68.
Casey birdied the par-3 second hole in the third round from 6 feet, and he was on the verge of getting within one shot of Piercy with a 4-foot birdie putt on the next hole until he missed it. Two holes later, the lost ball led to double bogey.
Wagner, meanwhile, plodded along. He was short of the green on No. 8 when he chipped in for birdie, and his chip from short of the ninth green lipped out. He pulled within one shot of the lead with a short birdie on the 10th, and caught Piercy with a 30-foot birdie on the 12th.
Piercy fell out of the lead with a bogey from just off the 14th green.
Kizzire started the third round six shots behind and made up ground quickly with five birdies on the front nine, only one of them longer than 12 feet. He finally dropped back in the rain, three-putted the 14th when his birdie attempt rolled some 6 feet by.