Jordan Spieth reacts in the Valero Texas Open at TPC San Antonio Oaks Course on Sunday in San Antonio, Texas. Photo: VCG

Former world No.1 Jordan Spieth ended his near four-year victory drought Sunday, gearing up for this week's Masters with a triumph at the US PGA Tour Texas Open.

Spieth, who hadn't won since capturing his third major title at the 2017 British Open at Royal Birkdale, signalled he's again a force to be reckoned with as the game's best look toward the first major championship of 2021 at Augusta National.

"This is a monumental win for me," Spieth said. "It's one that I've certainly thought about for a long time."

Spieth fired seven birdies in a six-­under-par 66, holding off tenacious playing partner Charley Hoffman to win by two strokes with an 18-under-par total of 270. Hoffman had cut Spieth's lead to one before Spieth birdied the 17th hole at TPC San Antonio, Hoffman's own 66 putting him on 16-under 272.

Now Spieth heads to Augusta National, where he was just 21 when he won his first major title at the 2015 Masters, going on to win the US Open the same year.

After years in the wilderness, the 27-year-old American had been knocking at the door, holding the 54-hole lead at both Phoenix and Pebble Beach this year.

He was tied for the lead going into the final round on Sunday with England's Matt Wallace, with Hoffman two shots back. Wallace closed with a two-under-par 70 for third place on 274.

"I actually felt really light, felt like I just wanted to come out and smile and try to have some fun," Spieth said, adding that "lightness" was something he'd struggled to find even as he contended earlier this year. "I never really doubted in myself to be able to get back to where I wanted to go, but when you lose confidence it's a lot of times hard to see the positives going forward." 

Spieth got his day going with birdies at the second and third - where he stuck his tee shot two feet from the pin.

He followed a bogey at the fourth with an 11-foot birdie at the sixth and six-footer at the eighth.

He kept the momentum going with a par save at the 11th, where his second-shot from 116 yards out found a greenside bunker.

He limited the damage with a seven-foot par-saving putt, then rolled in a 13-footer for birdie at the 12th that pushed his lead to three shots.

Playing partner Hoffman, who followed three birdies in his first six holes with a series of par saves, chipped in for birdie at the 13th to again narrow the gap to two strokes.

After Hoffman tapped in for birdie at the par-five 14th, Spieth rolled in his eight-foot birdie to maintain the margin.

And he kept rolling with a par save at 15, where he was short of the green from a tough lie in a fairway bunker but chipped to within a foot.

Hoffman applied the pressure with a 20-foot birdie putt at the par-three 16th, where Spieth's putt from off the green left him a tense short putt for par.

He made that, then pushed his lead back to two with a five-foot birdie at 17, both Spieth and Hoffman making par at the par-five 18th.