Real Betis is monitoring 28-year-old Greek centre-back Panagiotis Retsos, having also shown interest in him during the summer. Retsos is a high-priority consideration for the Spanish club due to his profile and could be a solution if their centre-back Nathan leaves in January. However, Olympiacos does not want to sell the player, who has also recently been linked with VfB Stuttgart and TSG Hoffenheim.