Complex sentence: They accepted the invitation for the tournament, but withdrew before their match against Carly Gullickson and Bernard Tomic and were replaced by Akgul Amanmuradova and Rik de Voest.
Split into simpler sentences: They accepted the invitation for this tournament, but withdrew before their match against Carly Gullickson and Bernard Tomic. They were replaced by Akgul Amanmuradova and Rik de Voest.