Bogeys on the 13th, 17th and 18th holes dropped the Australian two strokes behind leader Beatriz Recari on Saturday with one round left at Aviara Golf Club.
Despite her troubles, Webb, who shot at 2-under 70, remained confident about her chances at capturing her first LPGA Tour title since the 2011 Founders Cup in Phoenix.
"I played really well, just a couple of bad swings on 17," the Hall of Famer said. "And then the anti-right swing off the tee on 18. So just not a great, great finish. But obviously only two shots behind and I feel good with how I'm playing and I've just got to do that again tomorrow.
Recari had no such problems down the stretch. An eagle on the 16th boosted her finish. She drove the green on the 285-yard hole to set up a 4-foot eagle putt and finished with a 69 as she remained on top for the second consecutive round.
"Well, we were waiting on the tee and I hit that tee shot in the practice round, actually in the pro-am, and you just had to kind of play it safe," Recari said. "And if you get a good bounce, you knew that it was going to bounce left.
"If you got a good bounce on the green, great, even though just to make sure that I'm on the right side and I have enough green to work with. But I hit a very good tee shot and I had a good bounce as well so I had like a (4-footer) for eagle and I made it.
Recari, the 25-year-old Spaniard who won her lone LPGA Tour title in 2010, had an 11-under 205 total. She also completed her third round without a bogey
"I don't think I have every played bogey-free after three rounds," Recari said. "I mean, I've minimized mistakes, I've had a few bogeys, I've had one or two bogeys, but bogey-free, I think that's a new record for me."
She also hopes her past track record repeats itself Sunday.
"The last time I was in the lead heading into the fourth round was when I won, so it feels good," Recari said.
Paula Creamer and I.K. Kim were three shots back. Creamer had a 71, and Kim shot 70.
"You know I'm obviously disappointed in my finish and the last couple holes, the three-putt on 16 and the three-putt on 18," Creamer said. "Actually, all of my bogeys were three putts. My speed struggled, I made a good long one on one hole, on the second hole, but just kind of struggled with my pace out there.
"I'm not disappointed, but I'm not, you know, sitting over here super excited with the way I finished. But we have another day, I'm only three back considering everything that went on today and I'm looking forward to it.
Stacy Lewis, playing her first event since taking the No. 1 spot in the world from Yani Tseng with a victory last week in Phoenix, was four strokes back after a 69. Trying to win her third straight tournament, Lewis had an eagle on the par-5 eighth.