Lefty missed a birdie putt on the first hole that would have earned him $200,000.
The $9 million payout on the line wasn't enough at stake for Mickelson on Friday, so he decided to make a side wager with Woods on the opening hole.
"So I've thought a lot about this and there are spots out on the course that are some great spots for a little challenge and the challenges are coming directly out of our pockets, okay?" Mickelson told reporters on Tuesday. "And I feel like the first hole is a great hole for me. And I believe—in fact I'm willing to risk $100,000 that says I birdie the first hole. So that's how good I feel heading into this match."
It seemed like a solid bet at the time. Mickelson finished the 2018 PGA Tour season ranked sixth in birdie average with 4.31 per round.
Unfortunately, the risk didn't pay off for Mickelson. At least he still has 17 holes left to prove he's better than Woods and leave Las Vegas with a lot of money in his wallet.