Austin scored two touchdowns and the rookie running back carried the Rams in the second half, rushing for all but two of his 146 yards after the break.
"Just watched the tape.. By no means did they do anything special, we beat ourselves..." he wrote, before later deleting the tweet.
The Cards' defense let Austin get loose for six catches, 96 yards and the two scores. It then couldn't bring down Gurley, who rumbled over a heretofore stout front to seal the victory.
The division rivals meet in St. Louis in Week 13.