Finau started to backpedal during his celebration when he took a bad step and appeared to dislocate his ankle.
GT stepped up, landing his tee shot on the green from where it rolled back down the slope at an angle and into the hole for an ace, with loud cheers ringing around the course. When he got up, it looked like he snapped his ankle back in place.
The 34th-ranked player in the world, Finau is scheduled to make his first Masters appearance on Thursday.
No player has won the Par 3 and gone on to win the regular tournament, but that won't be a problem this year for Watson, who had just one mission this week.
Minutes later Jack Nicklaus's grandson, Gary, on the bag for gramps, holed out a tee shot on the 9th, sending a charge through the property and tears to Jack's eyes. Unbelievable moment for the Nicklaus family, and Jack went as far as to tell ESPN's Tom Rinaldi it was the "No. 1 moment" for him in golf. That was his first hole-in-one.
Nicklaus finished on four under for the Par 3 Tournament, with Watson winning it outright on six under.
"What I did didn't make any difference to me. It was a very special day, one I'll never forget". The streak will continue this year, as 68-year-old Tom Watson won the Par-3 and will not be playing in the Masters. "I mean what a day".