 Complete the following phrase:  As an amateur, Cahill reached the main stage of the 2019 World Snooker Championship, becoming the first amateur player ever to qualify for the event. At the tournament, he defeated world number one Ronnie OSullivan 108 in their first round match. OSullivan was the second former world number one Cahill had defeated in the 201819 snooker season, after his victory over Mark Selby at the 