Sullivan became the fastest swimmer in history after he broke the world 50 m freestyle record at the 2008 NSW Open Championships at Sydney International Aquatic Centre.
On 11 August 2008, he broke the 100 meter freestyle world record in the first leg of the 4x100 relay with a time of 47.24,[REF] Australia finished under the previous world record, broke the Oceania record and finished third in the relay in a time of 3.09.91