Berger's 63 wows at Bay Hill; JT returns with 79

ORLANDO, Fla. -- Daniel Berger made nine birdies, all but one of them inside 10 feet, for a 9-under 63 at Bay Hill -- a round no one was expecting Thursday in the Arnold Palmer Invitational.

Berger posted his bogey-free round in the morning, and by the end of the day, he had a three-shot lead and a score that was nearly nine shots better than the average of the 72-man field as only 32 players broke par.

Collin Morikawa, last year's runner-up, was in the middle of the pack until closing eagle-birdie-birdie for a 66.

Also shooting 66 was Ludvig Åberg, whose round in the afternoon, when the wind began to gust and swirl, was three shots better than anyone who played late. After beginning the back nine with back-to-back bogeys, he hit 5-iron to 25 feet for eagle on the par-5 12th.

Scottie Scheffler played in the midmorning and shot 70, his first opening round under par since his first tournament of the year (which he won). Rory McIlroy played late and was slowed by a shot off the rocks and into the water on the 13th for double bogey, and a bogey on the 18th for a 72.

"It has that U.S. Open kind of feel to it," Berger said of Bay Hill. "I think the course is just going to get tougher as the week goes on. The greens are going to get firmer. ... So yeah, just hit it in the fairway and try to make as many putts as you can."

Cameron Young had seven birdies in his round of 67. He also played in the morning. Another shot behind was a group that included Adam Scott and Xander Schauffele.

"You can shoot your way out of it on the first round because the score can get away from you," Scott said. "So if you're 5 over today, it's a long way back -- especially when there was a 9 under out there, which is hard to see."

Cognizant Classic winner Nico Echavarria went out in 30 and looked as if he might catch Berger, but the Colombian shot 42 on the back, including a triple bogey on the 12th hole.

Justin Thomas had a 79 -- a rude welcome back from five months away recovering from back surgery. He had a double bogey on the par-4 11th when he missed the fairway and missed a 3-foot putt, and another double on the 16th when a wedge from 81 yards went into the creek.

"It was kind of hard to say it was good to be back out," Thomas said. "Yeah, not obviously how I expected it to go. But the rust aspect kind of unfortunately was a little bit of what I anticipated."

The Associated Press contributed to this report.