The 26-year-old Spaniard, tied for the lead after finishing the delayed second round on Saturday, started the third round with a birdie on the third hole but his stuttering short game yielded a double-bogey on the par-five eighth.
Birdies on 14 and 15 offered a glimmer of hope but a fluffed putt on 18 for bogey saw Rahm punch his fist in frustration as he ended the day tied for seventh and seven strokes adrift of leader Dustin Johnson.
Asked how he thought the day went, he responded with utter incredulity: "Seriously?"
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"How would I describe (it)? Pretty awful," said Rahm, who hoped to break through at Augusta to claim his first major after a productive 2020 saw him enjoy victories at the Memorial and BMW Championship and earn a brief stint atop the world rankings.
"I didn't make a single putt. No way I can be happy about it," added Rahm, who finished Saturday's play tied with Colombia's Sebastian Munoz and American Patrick Reed.
"The golf course was there for scoring, I was playing good, and couldn't take advantage of anything... Fought my ass off at the end to try to salvage an under par round, and I couldn't." (Reporting by Andrew Both; writing by Amy Tennery; Editing by Ken Ferris)
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