Harris English watches his tee shot down at the second tee during the final round of the St. Jude Classic golf tournament on Sunday, June 9, 2013, in Memphis, Tenn.

MEMPHIS - The support of a handful of old high school buddies from Chattanooga, the calming influence of a veteran caddie and timely putting were exactly what Harris English needed to pull out his first PGA Tour victory.

English won the St. Jude Classic on Sunday, birdieing two of the final three holes to hold off Phil Mickelson and Scott Stallings by two strokes.

"I had probably 10 high school friends out there today," English said. "And I know that if I make a birdie or a bogey, they're probably going to be the same and they're rooting me on. I was just really relaxed out there today. Bogeyed eight and nine, which was tough. But I knew if I kept it together on the back nine, I could make a run at the thing."

The 23-year-old former Georgia star in his second year on tour survived a final round where he had six birdies and five bogeys. He finished with a 1-under 69 for a 12-under 268 total to get the victory in the same state where he helped Baylor School in Chattanooga win four Tennessee high school golf titles.

English said caddie Brian Smith also helped him refocus as he made the turn.

"I really didn't think I'd be in this seat right here coming off 9," English said. "I thought I kind of made some really dumb bogeys on eight, nine and kind of shot myself out of the tournament. But Smitty was saying, 'Hey let's go beat this back nine. Let's get back under par for the tournament for the day, and let's get after it.' So it was almost pedal to the metal."

English got four of his birdies on the back nine and saw on No. 14 that he was the lead at 10 under. He made a 5-foot birdie putt on No. 16 to tie Stallings for the lead, but Stallings bogeyed No. 18 to give English the lead to himself. English made a 17-foot birdie putt on No. 17, and overcame shaking hands as he two-putted No. 18 to pick up the winner's check of $1,026,000.

"It's quite an unbelievable feeling," English said.

Mickelson shot a 67, and Stallings had a 68. Mickelson said English finished strong and has been playing some great golf, but the four-time major winner got most of what he wanted after not playing the previous three weeks as he tuned up for the U.S. Open at Merion Golf Club.

"I'm really encouraged with the way I hit my irons," Mickelson said. "Got to get the 3-wood in play a little bit more, although next week at Merion distance won't be as critical as TPC Southwind. I'll be able to hit higher and softer shots."

English became the fourth player to win the event in his first start since the tournament moved to TPC Southwind in 1989 and the second straight after Dustin Johnson a year ago.

The final round returned to normal Memphis weather with the temperature reaching the high 80s along with the wind blowing from the south at 10-15 mph as it usually does at Southwind.

English won the Southern Amateur in 2011 and was an amateur when he won on the Web.com Tour at the Nationwide Children's Hospital Invitational in July 2011. He moved to the PGA Tour in 2012 and finished 79th on the money list. Now he has his fourth top 10 this year and a precious invitation to the Masters for the Georgia native.

It looked as if Stallings, a two-time winner on tour, would add his third win in three years when he took advantage of consecutive bogeys by English on Nos. 8 and 9 to go up by three strokes. Stallings was 12 under at the turn with four birdies on the front side. But he finished with a double bogey, a birdie and a bogey in his final four holes.

"You have to learn from the experiences that you have like this today and hopefully I'll get a little bit better break next time," Stallings said.

Shawn Stefani, a 31-year-old rookie from Texas, went into the final round with a one-stroke lead, had a 76 to drop into a tie for seventh at 6 under.

English, playing with Stefani in the final group, rallied after his consecutive bogeys.

He birdied No. 10, rolling in a 14-footer from the fringe, and hit his tee shot within 5 feet on the par-3 11th for his second straight birdie and fourth of the round. His fifth bogey of the day, at No. 12, moved him back to 10 under.

Stallings went to 11 under with a birdie on the par-5 16th but missed his own birdie attempt from the same distance a couple feet away on the green, which cost him when English birdied No. 16 a few minutes later to tie him again atop the leaderboard. English then birdied No. 17 when he was just trying to get close.

"It went in dead center and gave me a lot of momentum going into 18," English said.

On No. 18, Stallings hit his tee shot way right between the fairway bunkers and the cart path and put his approach into the right rough 83 feet away. His chip just reached the edge of the green, leaving him nearly 40 feet to the hole. He ran it 5 feet past the hole for a bogey.

"Harris has played great coming down the stretch," Stallings said.

Mickelson birdied Nos. 13 and 16, but he just missed a 13-footer for birdie on the par-4 17th. He then went right at the hole on No. 18 from 151 yards and just missed, leaving a 2-foot birdie putt to tie Stallings at 10 under.

English then finished off the win and celebrated with a simple fist pump.

Notes: The others to win in their first trip to this event at TPC Southwind were Lee Westwood (2010) and Dicky Pride (1994). ... English is the 11th American to win this event since 2000 and the seventh to come from behind in the last eight years here. ... English is the eighth player in his 20s to win this year compared to 15 last year. ... Brad Fritsch finished the tournament in style, holing out from the 18th fairway from 177 yards out. That put him at even par and tied for 56th.