Rory McIlroy's sports psychologist Bob Rotella says it was "part of the game plan" to not engage with playing partner Bryson DeChambeau during the final round of the Masters.
McIlroy, 35, achieved golf's career Grand Slam on Sunday with his first victory at Augusta.
American DeChambeau, who narrowly beat McIlroy to win last year's US Open, started the day two shots behind his partner.
He briefly led on Sunday after a birdie on the second coupled with McIlroy's double bogey on the first but eventually finished tied for fifth.
DeChambeau, who plays on the PGA Tour's rival LIV Golf, was asked how McIlroy was feeling after he signed his scorecard and replied: "No idea.