While the return to competitive action of tournament host Tiger Woods has dominated the headlines at Riviera Country Club, McIlroy will be focused on regaining top spot in the rankings from Masters champion Scottie Scheffler.

McIlroy hit the summit for the ninth time by successfully defending his CJ Cup title in October, the Northern Irishman finding the top spot after an absence of more than two years courtesy of his 23rd PGA Tour title.

Victory in January's Hero Dubai Desert Classic helped McIlroy remain No.1 until Scheffler defended his WM Phoenix Open title last weekend, the American moving 0.5 points ahead of McIlroy.

However, if McIlroy wins at Riviera, he will return to No.1 regardless of Scheffler's result, while outright third place would be good enough for McIlroy unless Scheffler finishes in the top-25 or Jon Rahm wins or is outright second.

Rahm can also become No.1 with a win or solo second in one of the PGA Tour's "designated," events, which features a prize fund of US$20 million ($A29.1 million) and has attracted 19 of the world's top-20.

Open Champion Cameron Smith, now with LIV Golf, is the only absentee, while World No.23 Joaquin Niemann also can't defend his title after joining the Australian on the controversial

Saudi-funded circuit and being banned by the PGA Tour.

The designated events are a key part of the PGA Tour's response to the threat posed by LIV, but Woods concedes they have generated mixed emotions as questions remain about the future format and access for lower ranked players.

"We are in the process of figuring all that out and it's been a variety of different models, different opinions, trying to figure out what is the best product and competitive environment and what we should do going forward," Woods said.

"Yes, limited fields, what's the number? Cuts? Yes or no. What's the number, what do we go to? How many players are playing the event? What is the ability to get into the designated events?

"How is Jay (Monahan, PGA Tour commissioner) able to sell our product to all the different sponsors across the board? There's so much give and take. It's still ongoing.

"It's been difficult. A lot of the players have been very forthright which is great, it's the way it

should be."