Harris English fought off the challenge of Phil Mickelson and Scott Stallings to claim his first PGA Tour win at the FedEx St Jude Classic in Memphis.

The 23-year-old birdied 16 and 17 to finish 12 under and keep a charging Mickelson at bay while Stallings' challenge finally faltered with a bogey on 18.

The pair would finish two shots behind English while Shawn Stefani, who was playing in the final group and had been in contention all week, shot a six-over par 76 that saw him fall out of contention.

A 65 on Saturday had put Padraig Harrington into contention but the two-time Open champion registered a 71 in the final round to finish on five under.

"I was feeling very good about my ball striking all week," English told Sky Sports 3.

"I just needed to get those putts to fall and I kept it together.

"I had bad bogeys on eight and nine but I stuck with it and made some good birdies coming in."

Stallings was the man in the driving seat in the early stages and reached the turn at 12 under but a double bogey on 15 dented his chances although he did pick a shot back up at 16.

Mickelson birdied 14 and 16 and when he played a sublime second shot on 17 it looked as though he may move within one of the leader but the left-hander could not make his putt and went up the last trailing by two.

His approach on 18 was even better as he put his second shot from the middle of the fairway to within two feet and completed a birdie to put the pressure on Stallings who was off the green.

And the pressure told on the 28-year-old who duffed his chip onto the very edge of the green. He two-putted to join Mickelson on 10 under and leave English knowing that a par-par finish was likely to hand him the title.

He went one better than that, though, as he played a tricky approach onto the 17th green and sunk a curling left-to-righter to head up the last with a two-shot lead that he would not relinquish.

Ryan Palmer finished one shot behind Stalling and Mickelson knowing a win would have seen him move into the world's top 60 and qualify for next week's US Open at the expense of Kyle Stanley but a closing 67 did not prove enough.

Ian Poulter double-bogeyed the first and, although he clawed a shot back on the third, the Englishman came home in 40 to shoot a 76 and finish a disappointing one over for the week.

Gary Woodland shot the low round of the day as he carded a 64 but that was only good enough to get him to four under for the tournament, one behind defending champion Dustin Johnson.