Shinnecock Hills reared its ugly head Thursday and got the best of three of golf's biggest names.
Rory had the worst score of the bunch, carding a 10-over 80, the highest U.S. Open round of his career.
Mickelson (77) and Spieth (78) weren't much better, as the trio recorded 20 bogeys and five double-bogeys on the day.
McIlroy had stated he'd be taking a more conservative approach off the tee at Shinnecock Hills this week to avoid the rough, but that strategy didn't pan out Thursday as he hit just seven fairways.
Meanwhile, Spieth's struggles on the greens continued, as he attempted 33 putts during the round and made a disastrous triple-bogey on his second hole after a chip returned to the exact spot he'd hit it from.
Considering Mickelson hit 13 of 14 fairways, his poor result was perhaps the most disappointing of the group, as he found trouble with his approach shots and putting.
Both McIlroy and Mickelson declined post-round interviews.
This grouping will have a chance to redeem themselves when their second round begins Friday at 1:47 p.m. ET.