Jim 'Bones' Mackay praised Jordan Spieth's caddie Michael Greller for gaining "the most critical yardage ever" during the American's Open win.
Greller was faced with a tricky yardage situation on the par-four 13th at Royal Birkdale during Sunday's final round.
Spieth had hit his tee shot so far right that he was forced to take an unplayable.
After a lengthy drop, Spieth and Greller were yelling at each other from nearly 50 yards away trying to get a proper yardage to the green.
Greller ultimately overruled Spieth's initial yardage, and it helped the eventual champion escape the hole with a bogey, a crucial moment as he claimed his third major.
"You could make the argument that was the most critical yardage ever given to a player in the history of golf," Mackay, now an on-course reporter for NBC Sports, said Tuesday, via golfchannel.com.
"Jordan is off the grid there, and Michael, once they found the ball, had to go to the top of the dune, he's got to eyeball it back to the ball, he's got to eyeball it toward the green, add it up, and give it to his man with hopefully the right line. If he gets that wrong, and the ball goes into a bunker or into a gorse bush, they are in a lot of trouble.
"What Michael did there, in his little piece, because obviously he's not hitting the shot, is one of the most amazing things a caddie has ever done."
The bogey actually dropped Spieth out of a tie for the lead, but he played his next four holes in five under to breeze past Matt Kuchar.
The relationship between Spieth and Greller, while in its early stages, has been compared to Phil Mickelson and Mackay's storied partnership.
Mackay is taking a little break from caddying after mutually splitting with Mickelson earlier this season.