Rory McIlroy has returned to the top of golf's world rankings for the first time since September 2015.

McIlroy and Brooks Koepka did not contest last week's AT&T Pebble Beach Pro Am, but McIlroy has moved above the American due to the vagaries of the two-year rolling ranking system.

However, both are in action at this week's Genesis Invitational, where Webb Simpson is set to be the only member of the world's top 10 not competing in a star-studded field at Riviera.

This will be McIlroy's 96th week in total as world number one, one behind the record for a European player held by Nick Faldo, although his lead over fellow four-time major winner Koepka is just 0.03 points.

McIlroy finished in a tie for third in his only previous start in 2020 at the Farmers Insurance Open, before which he discussed the prospect of becoming world number one again.

"I didn't know I was going to get a chance this early, but this has been a goal of mine for a while," the 30-year-old said.

"Winning four times last year, I closed the gap a little. There was a point in the middle of last year where I was four ranking points behind Brooks, which is a big gap.

"So it wasn't on the radar when I was flying back from Ireland after the Open, but then, once I'd won the Tour Championship and then won again in China, I kind of saw that gap closing. Then it sort of became, 'Huh, I'm actually close'.

"We all have egos out here and it would be great to get back there."

Spain's Jon Rahm is also within touching distance of top spot after two wins, two runners-up finishes and two other top-10s in his last six events.