Two of the greatest golfers in the world will go head-to-head in Las Vegas.
Woods and Mickelson have been embroiled in a rivalry for decades but this will be the first time they have faced off in a matchplay scenario.
And both have agreed to be audible to viewers throughout their rounds.
But how much does the winner look set to take home in prize money?
Tiger vs Phil: How much prize money is on offer?
The overall winner will take him a whopping £7m ($9m).
Tiger vs Phil: What bets have been made so far?
Mickelson cost himself £156,000 ($200,000) in just one hole as his multi-million pound showdown with Woods got under way.
Proceeds from lucrative side bets, including one the first hole, are reportedly going to charity.
At Tuesday’s pre-event press conference, Mickelson had bet 100,000 dollars (£78,000) he would birdie the first hole, Woods said double it and the wager was accepted.
But after an ideal tee shot on the 379-yard par four and an approach to eight feet, Mickelson missed his birdie attempt after Woods had also failed to convert from slightly further.
The second side bet was made on the par-three fifth hole.
Woods wagered $100,000 on who could get nearest to the pin.
It was Mickelson who had the last laugh though as his tee shot left him with just a six-tars putt.
More bets are set to be made throughout the round at Shadow Creek.