Kelvin Day knew his golf swing needed some work before the start of the Merrill Lynch Open. He hit the ball so poorly during Tuesday’s pro-am that he went straight to the range that evening to tinker with his swing.

The work paid off Saturday afternoon when Day shot a final round 6-under-par-66. The score vaulted Day past third-round leader Case Cochran, and to the win with a four-day total of 20-under-268 at Santa Maria Golf Course.

“I couldn’t find the center of the clubface at all,” Day said of his practice-round struggles. “I went and worked at the range Tuesday night and found something. It seemed to get better and better throughout the week.

“Today it really started clicking.”

Day was nearly flawless throughout Saturday’s round, hitting all 18 greens in regulation. The only stutters were a disappointing par at the par-4 eighth after hitting his approach to four feetand a three-putt bogey at 18 when the outcome had already been decided.

The win was the first for 26-year-old Day on the Adams Pro Tour. A native of Surrey, England, who played collegiately at Charleston Southern, Day said he plans to play the Canadian PGA tour later this summer.

Cochran, who shot 63 Friday, began the final round with a two-shot lead over Day. Cochran fell behind by a stroke at the turn but forged a tie at 19-under when he converted an 8-foot birdie putt at 14.

At the par-5 15th, Day boomed his drive 50 yards past Cochran and went on to make a two-putt birdie. Cochran settled for par and never held a share of the lead again.

“The 15th is a really tough green, and I wanted a wedge in there,” Cochran said of his strategy on the hole. “(Day) hit a heck of a drive and made birdie.

“I still went with what worked. I was playing well and doing what I had planned to do the whole week. I had been making pars and birdies, and I was sticking to it.”

Drew Evans began the day four shots behind Cochran at 14 under. Evans worked his way 19 under after a birdie at 15. But he lost his tee shot at 16 out of bounds leading to triple bogey, and went on to finish at 15 under 273 on the heels of a closing round of 69.

Brian Rowell of Lafayette was the top Louisiana finisher after carding a 69 on Saturday, good for a four-day total of 7 under 281. A pair of Baton Rouge golfers, Greg Berthelot and Brandt Garon shot even par. Berthelot was a 3 under 285, and Garon at 1 under 287.

Day started his round with two pars, but kicked his round into gear with three consecutive birdies. He two-putted from 15 feet at the par 5 third for his first birdie.

At the fourth, a monster drive and a short pitch left a two-foot birdie putt. Then he slid a 25-footer into the right side of the cup at five.

Day added a two-putt birdie at the par-5 fifth before missing a short attempt at the eighth. He nearly drove the ninth green to set up his fifth front-nine birdie.

“I felt like it was an easy 31 on the front nine,” Day said. “You don’t want to say it could have been better, but I missed the short putt on eight. It probably gave me a little more incentive to drive the green at nine.”

Neither Day or Cochran made a move on the back nine until Cochran’s birdie at 14. Day forged a two-shot lead with birdies at 15 and 16.

Needing to make eagle to have a chance at forcing a playoff, Cochran hit his approach at the par-5 18th into the water. He chipped up to save par while Day, playing conservatively, three-putted from 20 feet to wrap up his win.

“I was very calm the whole day,” Day said. “I think its because I’m swinging well right now. I’m in very good control of my golf game, and just tried to get out of my own way.”