Smith launched himself into contention at the elite, 63-man WGC – which boasts a US$10.25 million purse – courtesy of a 65 on Thursday at TPC Southwind in Memphis.

The 25-year-old's hot start, in a field featuring 45 of the world's top-50 golfers, left him at five-under-par and three strokes behind the lead.

Spanish ace Jon Rahm fired a red-hot 62 to top the leaderboard at eight under.

Smith, two-time Masters winner Bubba Watson and Patrick Cantlay, as well as Japanese duo Hideki Matsuyama and Shugo Imahira, all share second.

Fresh off being the only Australian to make the cut at last week's Open Championship, Smith mixed six birdies with a bogey to be well placed at the no-cut WGC.

Smith's resurgence, which gained momentum with a top 20 at The Open in Northern Ireland, comes after he missed four cuts from six events during a mid-year slump in the US.

But with this week's WGC and the PGA Tour's US$70 million playoffs looming, Smith welcomed the challenge.

RIGHT: Rahm leads the WGC Invitational at TPC Southwind. PHOTO: Stacy Revere/Getty Images.

Until recently, Smith had slid down the FedEx Cup points race and was facing a fight for his PGA Tour card – which expires this season following his 2017 Zurich Classic victory.

"I guess I am someone who likes a bit of pressure. I like having a motive or something extra to play for," Smith said at TPC Southwind.

"I was working hard all year, but results in the middle were poor.

"Now, I feel like my game is come back around and this is one of those times.

"I like TPC Southwind; you have to hit it straight and you have to chip and putt really well.

"I feel I can have three more good rounds and see what happens this week."

Marc Leishman is next best of the Australians at one under courtesy of a 69, while Adam Scott (70) was a stroke further behind at even par.

Scott's fellow former World No.1 Jason Day struggled during a 72 that left him at two over.

­- Evin Priest, Australian Associated Press