Cardiff City were shocked by Rotherham during pre-season, suffering their first defeat during their preparations for the new season.
Cardiff took the lead during the game, but Rotherham fought back and got themselves level.
Michael Smith scored the winning goal and ensured the newly promoted Championship team gave their Premier League rivals a serious jolt.
Josh Murphy had given Cardiff the lead, but his goal was cancelled out by Matt Palmer's excellent header.
Cardiff get their Premier League campaign underway against Bournemouth on the 11th of August.