Together with the transfer of Polak, Anderlecht also announced that Nemanja Rnic will leave the club. He'll play for GBA until the end of the season and won't return afterwards, since his contract ends.
And the club is already looking for a replacement for Rnic. According to La Dernière Heure, the Mauves are seeing Xavier Chen of KV Mechelen as a possible reinforcement. Chen enjoyed his training in Anderlecht, but was never able to make it into the first team. Therefore, he left. Now, he's back in the spotlights.