Tomas Ujfalusi has been ordered to pay €875,000 plus costs for breaking his pre-contract agreement with Sevilla.
The Czech Republic defender agreed to join the Ramon Sanchez Pizjuan outfit only to turn his back on the club.
Ujfalusi, who was out of contract at Fiorentina in the summer of 2008, opted instead to join Atletico Madrid on a free transfer.
Sevilla took the 31-year-old to court and won with the stopper now having to pay £800,000 for breaching his contract.
Ujfalusi, who can appeal the fine, helped Atletico finish fourth in the Liga table last season, while Sevilla finished third.