Xander Schauffele raised eyebrows Wednesday when he withdrew from the Sentry Tournament of Champions' pro-am. 

The seven-time PGA Tour winner, however, teed off in Thursday's opening round and shot 3-under 70. Afterward, he disclosed to reporters that he's dealing with an ailing back. 

Schauffele said he hasn't yet had an MRI and isn't exactly sure what the injury is, but has "everyone working on it" and hopes to get more information soon and "go from there." The world No. 6 was dealing with an injury at last month's Hero World Challenge, which is not something he is used to. 

"It's so new. Yeah, I don't really, I've been pretty good about everything for quite some time," Schauffele said when asked how long his back has been bothering him. "I'm 29 and Hero was like the first issue I've ever had. So this is new to me. That's why I don't know how to answer these questions. I've never had to do this. Hopefully, we don't have these conversations more often."

One of those questions was which part of his back is bothering him, to which he responded: "Just somewhere on my back, posterior chain. Yeah, I was moving. I walked around, swung. I attempted to swing the club a few times."

The 2019 winner at Kapalua added that the part of his swing that is most affected is his speed and he isn't 100% comfortable taking a full swing. 

"Need to get away from powderpuffing it and start lashing at it," he said.

Considering his back, however, Schauffele shooting 3 under (he's T-26, six shots off the lead) isn't all that bad, but he still expects better. 

"I needed to lean on my putter on days like this when you're kind of just chipping it around," he said. "When it's kind of cold and you don't feel great, you just chip it around and then you just got to make some more putts. You got to kind of score a lot better and I didn't really do that."

With another three rounds to be played, Schauffele hopes to make a run propelled by his short game, and maybe his back will hold up, too. 

"It's just a bummer," he said. "It's one of my favorite places to play, so hopefully that kicks into gear here in the next couple of days."