Staying true to the narrative of his entire career, Rory McIlroy’s first day as world No 1 in more than five years was eventful to say the very least. Two eagles in three holes allowed the Northern Irishman to leave Riviera Country Club on Thursday comfortable in the knowledge that he was still in the hunt at the Genesis Invitational. However, McIlroy will be looking for a second round containing the thrills but without the spills in Los Angeles on Friday “Yeah it was good - after a very sluggish start," McIlroy said after a 68. "I was one over through seven holes, 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. 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. 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 in his only previous appearance this year, 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." Having started on the 10th, those two “short ones” on the 11th and 12th amounted to no more than six feet each. After waiting for so long to return to the top of the rankings - for what, remarkable, is his eighth spell as No 1 - this was hardly the beginning he had envisioned. Yet a 35-footer on the par-five 17th set up an extraordinary trio of holes around the turn that featured him bogeying the 18th - after missing the fairway - and then grabbing another three on the par-five first, when hitting his approach from 180 yards to three feet. From there he made seven pars and birdie - on the fifth, where he holed from 15 feet - to sign for a three-under total, four behind the early pacesetter, Matt Kuchar. “In the afternoon tomorrow this course 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,” McIlroy said. “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.” In truth, McIlroy turned mediocrity into satisfaction, at the same time as outscoring Brooks Koepka, who he replaced as No 1 on Monday. The American requires at least a top-seven placing to earn his crown back at the first time of asking and his 69 was far less erratic than McIlroy’s opening salvo, featuring three birdies and one bogey. Koepka’s two-under effort was nowhere was near as stressful to watch, but it still boasted a Seve-like highlight on the par-four second when he pushed his drive into the trees. There were seemingly no other options than chipping it out sideways or trying to cajole it through a small window to the green. But Koepka decided to go sky-bound, somehow sending it over the trees and to within 15. He holed the putt for a birdie. Of course.