Portugal Colonial - McIlroy grabs first-round lead at Arnold Palmer Invitational

The Northern Ireland star, who won the event in Orlando in 2018 and has top-10 finishes in his last five appearances, had a two-shot lead with afternoon starters still on the course.

"I feel there's a nice flow to this golf course where you can really build a score," McIlroy said.

"You have par-fives, one every few holes, and you've got a couple of scorable par-fours. As long as you don't do anything stupid and you keep it in play, you feel like you can sort of methodically build a score on this golf course.

"I played the par-fives particularly well, and that was the bulk of the score," added McIlroy, who had three birdies and a 41-foot eagle putt to play the four par-fives in five-under.

McIlroy teed off on 10 and missed an eight-foot birdie chance at his opening hole. He was unable to get up and down from off the green and made bogey at 11.

But he followed a two-putt birdie at the par-five 12th by a birdie from the fringe at 13.

He rolled in his 41-foot eagle putt at 16 then birdied 18 to make the turn four-under.

Back-to-back birdies at the third and fourth saw him grab the solo lead and he made his last birdie of the day at the par-five sixth.

McIlroy said iron play was the key to his success on the par-fives.

"I hit a four-iron into 12 and a four-iron into 6. They were probably two of the best long irons I hit in a while. So when I start hitting long irons like that, I know my swing's in a pretty good place. Seeing shots like that certainly gives me some confidence."

Three players -- Beau Hossler, J.J. Spaun and former FedEx Cup champion Billy Horschel -- shared second on five-under par 67.

Spaun had five birdies without a bogey, Hossler bagged six birdies and Horschel had five birdies and an eagle at 16 -- where he landed his second shot 10 feet from the pin.

Horschel, who played in the afternoon, called his round "really good.

"When I did miss a fairway, fortunately I got some really good lies that I could advance up near the green," he said.

- Rahm stunner -

Half a dozen players were a further stroke back on 68, where Northern Ireland's Graeme McDowell was joined by South Korean Im Sung-jae, Australian Adam Scott, England's Ian Poulter and Americans Charles Howell and Will Zalatoris -- the reigning PGA Tour rookie of the year.

World number one Jon Rahm of Spain, playing the tournament for the first time, opened with an even par 72 that featured four birdies and four bogeys.

One of those bogeys included a shocking missed putt from within a foot at the par-three seventh.

Rahm, who momentarily appeared to be halting his stroke but didn't, and left the putt short.

"I wish I could give you all the excuses in the world, but no," he said. "It just didn't feel good in my hands, and I tried to stop, and I didn't. I just simply didn't stop. I don't know. It was very odd.

"It's not like it affected my play the rest of the day because I played really good," he said. "But sitting at one-under I feel like would feel a lot better than even par. It just sucks to give that one away."

P.Serra--PC