Rory McIlroy began his eighth spell as world number one with some flashes of brilliance in an opening three-under 68 in the Genesis Invitational.

McIlroy managed just one birdie in the first round at Riviera but also recorded two eagles in the space of three holes around the turn to make up for a sluggish start.

Day one ended with the Northern Irishman sharing seventh place, four shots off the pace after American Matt Kuchar's brilliant seven-under 64.

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Starting from the 10th, McIlroy had to hole from seven feet for par on the driveable par four after needing two attempts to escape from a greenside bunker. He also had to save par from sand on the 14th and 16th.

A perfect drive on the par-five 17th was followed by a fairway wood to the heart of the green from 289 yards. McIlroy nonchalantly holed the eagle putt from 35 feet to move into red figures.

McIlroy promptly dropped a shot on the 18th after missing the green with his approach but swiftly made amends on the short par-five first with a second eagle of the day from close range before carding his only birdie on the fifth.

Matt Kuchar is top of the leaderboard

"(It was) good after the start," McIlroy told Sky Sports. "I was one-over through seven, missed a couple of short ones early on and then went through a stretch of missing a lot of greens.

"I got it up and down on 13, 14, 15, so that was nice to not drop any shots there and then the eagle on 17 kick-started things for me a little bit. I played my second nine a lot better than I played my first nine so I feel good."

McIlroy, who finished in a tie for third at the Farmers Insurance Open on his only previous appearance in 2020, added: "I've been working on a couple of things the last couple of weeks since Torrey Pines. There was some stuff I saw there that I was trying to get away from.

"I weakened my left-hand grip a little bit again, just to neutralise the ball flight a little bit. I feel like I can release the club head and the ball's not going to go left."

Kuchar, the world No 20, set the clubhouse target on seven-under-par thanks to his bogey-free round early in the day.

Sharing second after rounds of 67 were Americans Russell Henley, Wyndham Clark, Adam Schenk and Harold Varner III, along with South Korean Lee Kyoung-Hoon.

Nine players were on three-under with McIlroy, including Australia's Jason Day, while England's Paul Casey was in a large group on two under which included America's Brooks Koepka and tournament host Tiger Woods.