Before 1300, Matthew entered into negotiations with the representatives of King Charles II of Naples and reassured him that he would assist the claim of his grandson, Charles for the throne against King Andrew III. However, in the summer of 1300, Matthew visited Andrew's court, but the king, the last male member of the Árpád dynasty, died on 14 January 1301, and following his death a rivalry broke out among the several claimants for the throne. At that time, Matthew's brother, Csák died childless and therefore Matthew inherited his possessions.