Complex sentence: Mayweather initially stated that he would be open to the possibility of a rematch with Pacquiao once he had recovered from his shoulder injury, but he changed his mind before talks of a rematch were in the works.
Split into simpler sentences: Mayweather initially stated that he would be open to the possibility of a rematch with Pacquiao once he had recovered from his shoulder injury. But he changed his mind before talks of a rematch were in the works.