Englishman Chapman was eligible after winning the US Senior Open last year.
Scott Stallings will take Chapman's place in the field at Merion Golf Club, west of Philadelphia. from June 13.
The 28-year-old Stallings missed out on an automatic place after finishing fourth at the Memorial but after shooting 70-69 at qualifying in Memphis, he was chosen to step up as first alternate.
The Massachusetts golfer admitted to the Knoxville News Sentinel that he thought the call from the USGA was a prank at first.
“I said, ‘Which one of my friends called you and told you (to do this)?’” he explained.
“He said, ‘No, this is real. We just got out of a meeting.’ I said, ‘Absolutely. I’ll be honoured to be there.’”
It will be Stallings's debut at Merion, though he says he has caddied there before.
"I walked off it – and I just caddied – and said, ‘That’s the hardest golf course I’ve ever seen,’” he said.
“Now, after being on Tour for a little bit, you have a new appreciation for how to play it.”
- Sports & Recreation
- Merion Golf Club
- Scott Stallings