Liverpool. We always have a massive friendly rivalry when I play as Villa, I lost every game for two seasons against them (got drawn against them in the FA Cup and the League Cup final), then drew our next game, and won the last one. It was pretty much the most proud moment of that career.
At Seoul, ******* Daejeon. They finished second last in the league, and both games against them were draws. They were embarrassing, but we had so much bad luck, I swear we hit the post with around three quarters of our shots.