Jason Day is as mercurial as they come on the PGA Tour.
The world's top-ranked golfer is just as likely to pull out with an injury as he is to lap the field by five or more strokes. One of his good friends, Tiger Woods, was forced to withdraw from this week's Genesis Open at Riviera Country Club due to ongoing back pain, which is something Day knows too much about.
Day missed over three months of action last fall due to back pain, which also forced him to withdraw from two FedEx Cup playoff events. He understands Woods' cautious approach to healing.
"It's hard. I just don't know, I've never had surgeries on my back before," Day said in his press conference Tuesday. "Obviously I've had back problems, but I don't know what the feeling is coming back from a back surgery let alone three back surgeries and then flying across to Dubai, whatever that was, 20 hours or so from San Diego, and then having to fly back here.
"I think it's a double‑edged sword for him because he has to come out and play and play tournament golf, but you have to watch also your back and make sure that's healthy because you have to play golf to get tournament ready and get the competitive rounds under your belt and get those juices flowing again, but also in the same regard you have to be wary of is your back 100 percent."
Woods, of course, missed the cut along with Day at Torrey Pines a couple weeks ago while being paired with each other. The 14-time major champion was then on pace to miss the cut again in Dubai before withdrawing after Round 1.
Day, who looks destined for a career of lingering injuries himself, said he would take 40 years old as a stopping point in his career.
"Ten years, if that's 40, I'm okay with that. Forty's okay, I've had a good career," Day said. "It's tough to say. I mean, any injury is terrible, but back, I mean, I've had so many, it's too much to explain. I'm just trying to extend my longevity of my career and I always say that if it is me in 10 years, so be it. But I'll end up quitting the game or walking away from the game at the moment that I don't want to improve anymore.
"The moment I don't want to improve and I don't want to play to win tournaments is the moment that I'll walk away and I'll be happy with it because I just can't keep fighting myself about it. So hopefully I can stay healthy and get to 40."
Pairings for the first two rounds came out Tuesday, and Day will play alongside Justin Thomas and Hideki Matsuyama, two of the hottest players in the game, Thursday and Friday.
"(I) actually had breakfast with Justin this morning," Day said. "Obviously I think three wins this year, which is spectacular. The two in Hawaii is obviously phenomenal with the 59 in there, and the way Hideki's been playing over the last six months or year really, he's been playing tremendous. He's one of the those guys that goes under the radar really.
"No one really thinks about Hideki too much and then he's always there. To be honest, he's just as good as anyone else. Like you said, he's one of the hottest players right now in the world and deservedly so because of the results that he's had.
"I've always thought that he's going to be a great player and a very dominant player and he's shown that over the last year. But I have a lot of stuff ahead of me coming into this week playing against those guys and playing against the rest of the field, too."
Day will have to fight hard to keep his No. 1 world ranking this week with Dustin Johnson and Matsuyama able to jar the title out of his grasp.