HILTON HEAD ISLAND, S.C. -- U.S. Open champion Matt Fitzpatrick shot his best round on the PGA Tour with a 63 on Saturday for a 1-shot lead over Patrick Cantlay through three rounds at the RBC Heritage.

Fitzpatrick had six birdies and an eagle when he holed out from 149 yards away on the par-4 third hole. He was at 14-under 199, poised for his first tour win since that major title 10 months ago.

"For me, that's ideally the start you need on a Saturday, isn't it?" Fitzpatrick said of the unexpected hole-out. "It just gets you off to a good start."

Cantlay, who lost in a playoff to Jordan Spieth a year ago, shot 66 to move to 13 under and into position for another try at the tartan plaid winner's jacket.

Spieth was also again in the hunt, another stroke back after a 66. He's seeking to do something he hasn't in his career -- defend a title.

World No. 2 Scottie Scheffler and second-round leader Jimmy Walker were among five players tied at 11 under. Scheffler shot 69 and Walker 72.

Walker, who opened 65-65, reached 14 under and was tied with Fitzpatrick before blowing up with three bogeys on the back nine and falling back.

Walker missed a par putt inside 2 feet on the 11th to fall out of first. Then, his tee shot on the par-3 14th caromed off a wood piling and way off the green, leading to a second bogey.

On the par-5 15th, Walker's second shot appeared to stay in one of the tall, stately trees that front the green, or at least there was no video evidence his ball splashed into the water hazard alongside. Walker took a 1-stroke penalty and had a third bogey in a five-hole stretch.

Masters champion Jon Rahm gave spectators who've celebrated his second major victory all week something to scream about at Harbour Town Golf Links when he opened with three straight birdies and closed to within 3 strokes of the lead.

But the feel-good, Rahm-com storyline fell apart on the par-3 fourth when his tee shot stopped on a wood facing short of the water. He followed with a one-handed backhand shot that stopped 65 feet from the cup and needed three putts for a double bogey. Rahm never found that same swagger the rest of the way.

The world's No. 1 player finished at 8-under after a 69 and is 18 holes away from a well-deserved rest after winning at Augusta National last week for his second major title. He'll return to the tour in two weeks to defend his Mexico Championship title.

Fitzpatrick has struggled much of the year, missing four cuts in his past seven events before arriving at Augusta National last week. That's where he finished tied for 10th and came to one of his favorite courses -- he has played this tournament eight seasons -- with confidence.

"I think this is a golf course that's shown that there are low scores around here this week," said Fitzpatrick, whose family took vacations to Sea Pines Resort when he was a child.

Fitzpatrick played Harbour Town as a young guy and took tennis lessons on the green clay courts that used to host the WTA's annual pro tennis tournament, now called the Charleston Open. How was his tennis game?

"Not as good as my golf game at the time," he said.

Fitzpatrick, who surpassed his previous tour low of 64 last accomplished at this venue two years ago, looks to add a championship trophy to his Harbour Town memories.

Cantlay has had four top-seven finishes at Harbour Town in five previous appearances. He had birdies on three of his first six holes to give himself a chance at another high finish.

"I've had a good track record around this golf course and had a number of chances, so should be nothing new tomorrow," he said.

Fitzpatrick was lowest on a picture-perfect Saturday custom-made for going low -- and plenty of golfers accomplished that at Harbour Town.

Former PGA Championship winner Keegan Bradley finished off a 64 before lunch, while Chez Reavie had a 65 to get himself into the top 10. In all, 37 of the 73 competitors finished in the 60s.