Davis Riley had a four-shot lead over surging Masters champion Scottie Scheffler on Saturday at the Charles Schwab Challenge, where PGA Tour pros were stunned to learn that 30-year-old colleague Grayson Murray had died.

The US PGA Tour said in a statement that Murray, who withdrew from the event at Colonial Country Club in Fort Worth, Texas, on Friday, had died suddenly on Saturday morning.

A cause of death was not immediately known, and tour commissioner Jay Monahan said Murray's parents had urged officials to continue competition.

"Obviously the news hasn't really sunk in quite yet, but I'm thinking about his family and praying hard for all of them," Scheffler said.

"I can't imagine how difficult of a time this is. I got to know Grayson a bit better over the last six months or so and there's not really a way to put into words how sad and tragic it is -- but I'm thinking about his family."

Riley, ranked 250th in the world and chasing a second US PGA Tour title, pushed his two-stroke overnight lead to four with a four-under par 66 that left him at 14-under 196.

Riley had five birdies on the front nine before back-to-back birdies at the ninth and 10th slowed his progress, but he bounced back with a birdie at the par-three 16th -- where he landed his tee shot within four feet of the pin -- to plump his cushion.

"I got off to a hot start," said Riley, whose previous title came alongside Nick Hardy in the 2023 Zurich Classic two-man team event.

"I was just playing some really solid golf, hitting a lot of fairways and greens, and got the putter going a little bit.

"Made one or two loose swings on nine and 10, and yeah, the last couple hours on the course were tough."

Riley said he was proud of how he handled the increasingly windy and frustrating conditions, and he was looking forward to playing alongside world number one Scheffler on Sunday.

"When you've got Scottie breathing down your neck you can't really let up any, so I know it's going to be tough and it's going to be a fun day," he said.

- Scheffler closes strong -

Scheffler climbed into contention with seven birdies in his seven-under 63.

Four of them came on the back nine, starting with a six-foot birdie at the 11th.

He rolled in a 15-foot birdie at the 15th and followed with 16-foot birdie putts at both 16 and 17.

He faced another 16-footer at the 18th, but settled for a two-putt par.

"I played nicely today," Scheffler said. "I got off to a pretty good start, had some nice up-and-downs there early in the round ... then I had those nice birdies coming down the stretch to move up the leaderboard a bit."

Scheffler has put together a remarkable season, his run of four wins in five starts including a second Masters triumph. But he's playing this week with multiple charges -- including felony assault of a police officer -- hanging over him after he was arrested and released following a traffic incident before the second round of the PGA Championship last week.

Police in Louisville say Scheffler disregarded signals from an officer directing traffic as he allegedly tried to go around a traffic jam as authorities investigated an earlier fatal accident.

Scheffler has called the incident "a huge misunderstanding".