Scott Stallings fired a 9-under 63 on Saturday to grab a five-stroke lead after three rounds of the Humana Challenge.
Stallings, who has yet to record a bogey, is 22-under-par 194 through 54 holes. The 27-year-old is seeking his third career PGA Tour victory.
"I've been aggressive," said Stallings. "I've been smart when I got out of position. Just because I played really good, doesn't mean that I've hit it perfect on every single hole. I scrambled a little bit, but when I got out of position off the tee, I played smart. I hit it in the middle of the green and just kind of accepted par and moved on and was really aggressive when I had the opportunity."
Overnight co-leader Roberto Castro carded a 69 at La Quinta Country Club and fell into a tie for second place with former British Open champion Stewart Cink (66), Charles Howell III (67), John Rollins (64) and Charley Hoffman (67) at 17-under.
Phil Mickelson, making his season debut, made the cut at 11-under. The lefty entered the tournament battling flu-like symptoms, but he has improved each day with rounds of 72, 67 and 66.
Defending champion Mark Wilson and 2012 U.S. Open champion Webb Simpson both missed the cut at 7-under and 8-under, respectively.
Brian Stuard tallied the low round of the day with a 62 at Nicklaus Private Course and moved into a tie for seventh place with Sang-Moon Bae (64), Kevin Streelman (66), Kevin Stadler (68), Brian Gay (67), Ryan Palmer (66), Billy Horschel (65) and Lee Williams (68) at minus-16.
Jason Kokrak (69), David Lingmerth (69), Nicholas Thompson (66) and Richard H. Lee (70) are knotted in 15th place at 15-under.
Rookie James Hahn held a share of the lead after both Thursday and Friday, but he stumbled to even-par in the third round to drop into a tie for 19th at 14- under.
World No. 8 Brandt Snedeker is also 14-under, 2012 Players champion Matt Kuchar is 13-under and rookie Russell Henley, who won the Sony Open in Hawaii last week, sits at minus-12.
After rotating between the Palmer Private Course and the Nicklaus Private Course at PGA West, and La Quinta Country Club, the tournament will shift to Palmer Private for Sunday's final round.
Stallings has already improved upon his Humana Challenge performance from a year ago, which saw him withdraw due to a rib injury. He is seeking his first PGA Tour win since capturing the True South Classic in July. This season, he tied for 13th at the Hyundai Tournament of Champions, but didn't survive the cut at the Sony Open.
Starting on the 10th tee at the Nicklaus Course, Stallings carded a pair of pars before scoring a birdie on No. 12 and an eagle on the par-5 13th. He added another birdie on the 17th and made the turn at 17-under -- one stroke behind Castro.
Stallings pulled even when Castro bogeyed No. 12 at La Quinta, then went in front for good with a stretch of three straight birdies, which began at No. 4. He was still holding a three-stroke lead when he dropped his approach within 20 feet on the par-5 eighth and drained a straightaway eagle putt to reach 22-under.
"The same thing goes tomorrow," Stallings said on his approach for the final round. "Obviously, a lot can happen coming down the back nine, especially with all the birdie holes coming in, but it is what it is, and go out there and try to be aggressive early and go from there."
NOTES: Castro is looking for his first PGA Tour win ... His lone top-10 finish during his rookie campaign in 2012 was a tie for seventh at the Greenbrier Classic... Cink has not won on the PGA Tour since capturing the Open Championship in 2009 ... The pros were joined by amateurs for the tournament's first three rounds.