Rory McIlroy overcame a stuttering start to roar into the mix with two eagles in three holes in the Genesis Invitational at Riviera Country Club.

The Holywood star (30) had to dig deep for his first seven holes as he followed a three-putt bogey at his third hole with some brilliant scrambling before flexing his muscles to card a three-under 68 that leaves him tied for seventh, four shots behind American Matt Kuchar.

It wasn't all plain sailing for the Co Down man, whose return to the top of the world rankings could be short-lived with Brooks Koepka and Jon Rahm both close enough to overtake him this week.

Scores

He started at the driveable 10th and found the back bunker but couldn't make the green from close to the back lip and had to make an eight-footer for par.

He's changed the set up of his TaylorMadeGolf Spider X putter this week, going for a 34.75-inch shaft as opposed to his usual 34 inches in an effort to soften his arms and posture.

It didn't appear to be working as he missed from inside five feet for birdie at the 11th and then came up short with his approach putt and missed another four-and-a-half footer, this time for par, at the 12th.

But he soon found his groove in the short game department and after getting up and down for pars at the 13th, 14th and 15th, he curled home a 12 footer for par at the 16th and played well from there, taking 26 putts and hitting six greens on the back nine after missing six on his opening nine.

With cold early morning conditions giving way to balmier temperatures, he blasted a big drive down the 596-yard 17th and drew a 290-yard three-wood to the heart of the before rolling in a 35-foot eagle putt to move into the red.

A bogey at the 18th, where he was blocked out by the eucalyptus trees on the right and failed to cut his approach back to the green, was only a minor blip.

He bounced back immediately with another eagle from just five feet at the 496-yard first, which he reduced to a three-wood and a cut seven-iron.

"It was good after the start," said McIlroy, who birdied the tricky fifth and ended his day four shots behind  Kuchar, who fired a seven-under 64 to lead by three shots from Wyndham Clark, Adam Schenk, Russell Henley, Harold Varner III and South Korea's Kyoung-Hoon Lee.

"One-over through seven, missed a couple of short ones early on and went through a stretch of missing a lot of greens. 

"But I got it up and down on 13, 14 and 15 and the eagle on 17 kick-started things a little bit."

Admitting his par save at the 16th was key, he added: "There are no easy putts on this golf course and that was nice.

"I feel that part of my game helps me stay in rounds and putt like that give you a little bit of momentum going to the next tee. 

"You hit a couple of good shots and get a bonus by holing a long one and all of a sudden you are one-under-par and things are looking okay again."

He matched young gun Patrick Cantlay and outscored Dustin Johnson by four shots as world number two Koepka, who could return to number one with two-way tie for seventh, eased to a 69.

"Very sluggish start," he said. "I made a good up-and-down for par on 10. To be fair, I hit a good tee shot and sort of went into the back of the bunker, and it was awkward. 

"I should have birdied 11 and then sloppy three-putt on 12. After that, I needed to get up and down on 13, 14, 15, 16 just to save par. And then eagle on 17 was sort of what started everything. None of us really got it going early on, but then you have 17 and then the first hole in a space of a few holes so you can make some red numbers there, which I was able to do."

Rahm —who could climb to world No 1 for the first time with a win, a solo second-place finish or a two-way tie for second— was three-under after 11 holes before signing for a one-under 70.

As for Tiger Woods, who is seeking a record 83rd PGA Tour win, the Masters champion eagled the first and birdied the fifth and eighth to get to four-under before he lost his swing and posted a two-under 69.

The veteran will be out early today and he's looking to make up ground on the leaders at a course where he has never won.

"Well, considering I'm still on east coast time, I kind of like it," Woods said. "I've been getting up pretty early, so it will be a quick turnaround, get back at it. 

"Hopefully we'll have a little bit smoother greens out there on the golf course. Hopefully I can hit it as good as I did on that front nine to give myself a number of looks for the entire 18 holes, not just nine holes." 

McIlroy will have to wait until the afternoon and he knows he will have to be patient in more ways that one if he fails to hit greens in regulation

“A few more greens I think more than anything else,” he said of his ambitions for round two. “I thought I drove the ball pretty well. Yeah, just a few more greens.

“Hitting it in the right spots maybe when you do give yourself chances here, especially with how firm and fast the greens are getting, just leaving your ball on the right side of the hole. There's a couple times today I hit good shots but was on the wrong side. You're being very defensive with your putt, you're trying to give it a good run at the hole. Yeah, just a bit of that.

"The afternoon tomorrow is going to play a lot different than how it played this morning, it's going to be dry again and the course is going to firm up.

"It's going to keep getting trickier and you're going to have to really think your way around this place. I'm looking forward to that."

Meanwhile, Royal Dublin's Niall Kearney carded a two-under 71 on the Links at Fancourt to lead the Irish challenge in the Challenge Tour's Dimension Data Pro-Am.

Scores

South Africa's Christiaan Bezuidenhout shot an 11-under 61 on the Outeniqua Course to lead by a shot from Spain's Santiago Tarrio as Robin Dawson shot 73 at the Links and Gavin Moynihan a two-over 74 on the Montagu Course.

The cut will be to 60 players and ties after round three with the final round on the Montagu Golf Course.