Complex sentence: Martina Navratilova referred to Raonic as "a new star" saying that "the sky is the limit" for the young tennis player, and the "Sydney Morning Herald" referred to Raonic as a "future superstar".
Split into simpler sentences: Martina Navratilova referred to Raonic as "a new star" saying that "the sky is the limit". The "Sydney Morning Herald" referred to Raonic as a "future superstar".