Irving, TX (SportsNetwork.com) - Steven Bowditch carded four birdies on the back nine Sunday to pull away from the field and win the Byron Nelson Championship by four strokes.

Bowditch closed with a 5-under 64 to end at 18-under-par 259. This was his second win on the PGA Tour, and his second victory in the state of Texas. He also won the Texas Open in San Antonio last season.

"Not really sure. Just stick to your routine and stick to your game plan. It's just one of those things, it's such a special place to me and I just wanted to stay patient out there," Bowditch said when asked how he stayed calm.

"I had been lacking the last couple of days (in making putts) and then finally down the stretch, they started to go in. It was great to be patient out there and wait for my time."

Charley Hoffman and Jimmy Walker had chances to put pressure on Bowditch, but Hoffman ran out of holes and Walker stumbled to a pair of bogeys early on the back nine. Hoffman (65), Walker (66) and Scott Pinckney (66) shared second place at minus-14.

Zach Johnson fired a 6-under 63 at a shortened TPC Four Seasons Las Colinas to grab fifth place at 13-under-par 264. Brandt Snedeker (64) and Jon Curran (68) tied for sixth at minus-12.

Dustin Johnson grabbed a share of the lead with a pair of early birdies, but a quadruple-bogey at the sixth dropped him four back and he never recovered. Johnson closed with an even-par 69 to end in a share of eighth at 11-under-par 266. He was joined there by 2012 champion Jason Dufner (66).

After chip-in birdies at the first and third, Dustin Johnson was tied for the lead with Bowditch. However, at the sixth, he knocked his first tee shot out of bounds, then found some long fescue grass with his next tee ball. That led to a quadruple-bogey for Johnson and he failed to get back into contention.

Walker converted back-to-back birdies at four and five to join Bowditch atop the leaderboard at minus-13.

Bowditch, who led by two to start the day, birdied the first, but stumbled to bogeys at three and five, dropping him to 12-under. He bounced back with a birdie at the sixth, then poured in a long par-saving putt at seven.

The Australian converted a birdie chance at the eighth to grab a 1-shot lead, and he was alone in the lead the rest of the way. At the drivable par-4 11th, Bowditch got up and down for birdie to push his lead to two.

Bowditch made it two in a row with a short birdie effort at 12 to move three clear of Zach Johnson, who was already finished. After a trio of pars, Bowditch birdied the 16th from 10 feet out.

The 31-year-old again made it two in a row with a birdie at the 17th. He parred the last to seal the win.

"Fourteen is a 100-yard par-3, but it can still jump up and get you just like a par-4. I hit a perfect golf shot and I just went long. I'm not sure why. I hit a really good bunker shot and made the par putt," Bowditch said of the 14th. "That was when the nerves and everything really started to kick in and I had to calm down and go shot-for-shot."

Walker followed his early birdies with five straight pars. Back-to-back bogeys at 11 and 12 dropped him to 11-under. He rallied for a share of second with an eagle at 16 and a birdie at 17.

Hoffman played the front nine in 1-over par, but birdied five of the first seven holes on the back nine to fly up the leaderboard. He parred the final two holes to end there at minus-14.

Pinckney, who was in the final group with Bowditch and Dustin Johnson, had two birdies and two bogeys on the front nine. Three birdies on the inward nine helped him tie for second.

NOTES: Bowditch earned $1.278 million for the win ... Due to heavy rain earlier in the week, the 14th was shortened from a par-4 to a par-3, which changed par to 69 ... The PGA Tour heads to Ohio next week for the Memorial, where Hideki Matsuyama earned his first tour win last year.