With all kinds of theories about Tiger Woods and his disappearing golf game, Jason Day says he sees conditional potential but could have an issue beyond golf.

Reuters reported that Day, the No. 10 golfer in the world, played nine practice with the No. 195 player at Chambers Bay in preparation for the U.S. Open earlier this week and talked about Woods' fragile mental state.

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The question is whether Day was referring to more than Woods' golf.

"Who knows what's going on with Tiger right now? We're friends, but I don't get into his personal life and I don't want to," Day told reporters while preparing for Thursday's opening round. "That's his stuff and he deserves his privacy.

"But when it comes to golf, it's very difficult because you could have all the tools in the world, but if you really don't want to be there or if there's something that's off course that's playing on your mind ...

"The game of golf is so mental and if you don't have everything in the right order, it's very difficult to win golf tournaments."

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Woods maintained his bravado during a media session Tuesday in assessing his U.S. Open chances, according to USA TODAY's For the Win.

"In all, Tiger was about as pleasant as he always is in press conferences - which can be safely classified as 'moderately pleasant' - but he still displayed the same hard edge that the media has grown used to. Especially during one of the questions, a reasonable one, when a reporter asked Tiger why he still thinks he can win a U.S. Open. He took a moment to absorb the question, calmly looked up, and answered succinctly:

"Um, I've won three of these"

Day confirmed that Woods' short game and iron play seem to be in order. It's Woods' driver that is giving him trouble.

"Tell you what, if he (Woods) could get on the fairway, he'd probably be back to where he was," Day said. "His iron play is just ridiculous, how good it is right now; it's really special.

"The three-wood is okay, the driver ... gets a little wide sometimes. That's the biggest thing for him right now is to really kind of get on the fairway."