San Antonio, TX (SportsNetwork.com) - Jimmy Walker carded a 3-under 69 in Saturday's third round and extended his lead to four stokes at the Texas Open.

Walker finished 54 holes at 9-under-par 207. He earned his fourth PGA Tour win earlier this year at the Sony Open in Hawaii.

Jordan Spieth, who was tied for the lead after a par at 13, played the final five holes in 1-over par to close out a round of 1-under 71. He is four strokes off the lead at minus-5 on the AT&T Oaks Course at TPC San Antonio.

Reigning FedExCup champion Billy Horschel also carded a 71 to improve into third place at 3-under-par 213.

Scott Pinckney shot 3-under 69 to jump into a share of fourth place at minus-2. He stands alongside Zach Johnson (72), Brendan Steele (72), Jason Kokrak (71) and Chesson Hadley (71).

Aaron Baddeley (76), Kevin Na (75) and Chris Kirk (73) are the final players in red figures at minus-1 and they are tied for ninth place.

Walker knocked in a 3-footer for birdie at the second to move to minus-7, but dropped shots on the next two holes. He found sand with his tee shot at the par-3 third and blasted to 56 feet. He 2-putted for bogey from there.

The four-time PGA Tour winner missed the green with his approach at the fourth and that led to his second straight bogey. Walker righted the ship with a 13- foot birdie putt at the sixth, but Spieth had caught him atop the leaderboard.

Spieth also bogeyed the third after finding sand off the tee. He converted back-to-back birdie chances from inside five feet at five and six. A 24-foot birdie effort at the seventh moved Spieth alongside Walker at minus-6.

Walker responded with a short birdie at the eighth to regain the lead. However, Spieth poured in a 21-footer for birdie on No. 9 to join Walker at 7- under.

After Spieth stumbled to a bogey at the 12th, Walker did the same. The 14th proved to be a critical hole. Spieth's second at the par-5 found sand and he dumped his third in another bunker. Spieth blasted to 14 feet, but he 2-putted for bogey to slip to minus-5.

Walker, in the group behind Spieth, stuffed his third inside two feet and kicked that in for birdie to move two clear at 7-under.

Spieth tried to fight back as he birdied the 15th. He pushed his tee shot well right at 16 and hit the grandstands. Spieth's chip came up short, then he knocked his third to four feet. His bogey effort stayed out and the double- bogey dropped Spieth three off the pace.

As Walker parred 15 and 16, Spieth got one shot back as he drained a 24-foot birdie putt at 17. He parred the last to end at 5-under.

"It was up and down. Great start. I was 3-under through nine, in these conditions, couldn't ask for anything else. And then, I just kind of let some get away from me there," Spieth said of his round. "I didn't play the smartest shots and was being a little too aggressive for this golf course."

Walker missed the green at the short par-4 17th, but chipped to seven feet and converted the birdie chance. He closed with a 10-foot birdie putt at the last to extend his lead to four.

"It was a tough day today. (The wind) blew really hard, again, out of the south today. So I know it's a windy golf course, but it's still tough," Walker said. "The greens are firm. You can see some spots starting to brown out a bit."

NOTES: The last nine 54-hole leaders on the PGA Tour have failed to hang on for the win ... Walker has won two of the previous three times he had at least a piece of the 54-hole lead ... Gary Woodland had the only bogey-free round on Saturday.