Joey Sindelar got the third round at Medinah off to a flying start by holing his second at the par-five 5th - only the third albatross in USPGA history.
Sindelar has won seven PGA Tour titles in a 25-year career
Having made the cut on the number, the 48-year-old smashed a three-wood 241 yards for a two at the 537-yard hole.
It was the first albatross in any major since England's Gary Evans in the 2004 Open at Royal Troon.
But the rest of the American's round was a very mixed bag - three birdies and seven bogeys for a one-over 73.
"It was a huge thrill," said Sindelar, who has had two hole-in-ones since joining the PGA Tour in 1984.
"The pin was back left and I was aiming seven or eight yards right of it so I was kind of stunned. They are all luck."