MEMPHIS, Tenn. — Travelling from Northern Ireland to Tennessee has left everyone who played four rounds at the British Open fighting jet lag.

Jon Rahm's putter helped him recover pretty quickly.

Rahm matched the lowest round of his PGA Tour career with an 8-under 62 on Thursday at the FedEx St. Jude Invitational, taking advantage of nearly perfect greens to open a three-stroke lead in the World Golf Championships event.

"I was pretty exhausted Monday and Tuesday, and that's why I decided not to do much on the golf course and just make sure mentally I was going to be ready to compete," Rahm said.

He spent about an hour on the putting green Wednesday. He didn't step foot on the front nine, his back nine, until he made the turn, and he had five birdies on that side.

Rahm rolled in five putts of at least 16 feet for birdies in the bogey-free opening round at TPC Southwind. The Spaniard finished with a 7-footer to save par. He also opened with 62s last year in his CareerBuilder Challenge victory and in January in the Farmers Insurance Open at Torrey Pines.

"That's what made it so comforting because I knew, especially with the greens being this pure, if I started a ball online I was going to have a chance," Rahm said.