Molinari, the Open champion, had a lead going into the back nine at Augusta before double bogeys at hole 12 and 15 handed the title to Tiger Woods.
The 36-year-old Italian claimed it took a “big effort” because he was unwell for all of the Masters.
“It took some time to recover physically because I wasn’t 100 percent all week in Augusta and I was taking antibiotics,” Molinari said.
“It was just a sore throat and a bug that I got from the kids at the beginning of the week.
“I think it was a big effort to do what I did, and probably on Sunday, when the adrenaline kind of went down, I felt how much I was spending energy-wise during those days.
“It was nothing major, and I was feeling well enough, obviously, to play well in Augusta.
“But I think sometimes in those circumstances, you ask a lot to your body, and then at some point you’re going to pay a price for it.”
Molinari will now be competing…