Greece international midfielder Kostas Katsouranis has been let go by Panathinaikos, the Athens club's new president, Giannis Alafouzos, announced on Wednesday at a team training session.
Katsouranis, 33, had been under contract with Panathinaikos until the summer of 2013 and was one of the best-paid players in the squad.
Katsouranis' departure comes a day before Panathinaikos are due to host Tottenham Hotspur in the Europa League.
Panathinaikos have made their worst ever start in the Greek Super League, having won just one and lost four matches so far, and they also lost their opening Europa League game last month when they fell 3-0 at Slovenian side NK Maribor.
Alafouzos and Portuguese coach Jesualdo Ferreira were reportedly not pleased with Katsouranis' performances on the pitch this season, nor with his conduct off the field.
Katsouranis has made 97 appearances for the Greek national team and was a member of the Euro 2004-winning squad.