Starting your final round with two pars and a birdie on the first three holes is something most players would sign up for. But for Justin Thomas, it was not enough to keep up with playing partner Marc Leishman and his good friend Jordan Spieth, each of whom made the turn in six-under 30 at TPC Boston.

Thomas, however, kicked it into another gear at the short par-4 fourth, driving it just short of the green and rolling in a 32-footer from the fringe for an eagle two. Spieth and Leishman ran into trouble on the back nine (the latter shooting nine-hole scores of 30-40), while Thomas closed the deal, making three birdies and just one bogey the rest of the way to card a five-under 66 and win the Dell Technologies Championship at 17-under 267.

The victory is Thomas’ fifth of the season, and sixth of his US PGA Tour career. It moves him to second in the FedEx Cup standings, and makes him the favorite to win the tour’s Player of the Year award. It also puts him in the same company as Jack Nicklaus, Tiger Woods and Spieth as the only players since 1960 to win five times, including a Major, in one season before the age of 25.

RELATED: 15 things you need to know about Justin Thomas

For Spieth, his Sunday was a tale of two nines. The three-time Major champion followed up his front-nine 30 with a two-over 37 on the home nine for a four-under 67 to finish three behind at 14-under 270. The runner-up finish moves him from second to first in the standings heading into the third leg of the FedEx Cup Playoffs.

Having built a two-shot lead over Thomas and Spieth at the turn, Leishman struggled on his final nine as well. His quest for a second title of 2017 ended when he came home in five-over 40 to shoot a one-under 70. He finished in solo third at 13-under 271 and now sits at seventh in the standings. It’s the Victorian’s sixth top-10 finish of the season, and fourth inside the top-six.

RELATED: The clubs Justin Thomas used to win the Dell Technologies Championship

Finishing in a tie for fourth at 12-under 272 were Paul Casey and Jon Rahm. Rahm stayed put at fifth in the standings, while Casey cracked the top-10 and now sits at eighth.

Four players tied for sixth at 11-under 273, including Phil Mickelson, whose final-round three-under 68 gives him four consecutive rounds in the 60s. For Mickelson, it’s his fifth top-10 this year, and saw him leap from 58th to 36th.

Multiple players made huge jumps to get inside the top-70 and earn a spot at the BMW Championship, including Stewart Cink, who went from 81st to 57th thanks to a solo 12th finish at nine-under 275. Spain’s Rafa Cabrera Bello entered the week at 80th, and made the move to 60th thanks to a final-round six-under 65 that got him in a tie for 18th at seven-under 277.

RELATED: FedEx Cup frequently asked questions

Emiliano Grillo, who finished in solo 22nd, jumped 15 spots from 77th to 62nd and will advance to the third leg for the second time in just his second year on tour.

Tour rookie Grayson Murray’s T-25 finish was enough to move him from 70th to 63rd, meaning he will make his first appearance at the BMW Championship in two weeks.

Rod Pampling, Russell Knox, Bubba Watson, Patrick Rodgers and Graham DeLaet all finished outside the top-70 and will not advance to the third event of the playoffs.