Apart from two singles titles (1988 Gstaad and 1991 San Francisco), Cahill made a semifinal appearance at the US Open in 1988, defeating Mats Wilander and Andre Agassi among others.

From his 13 doubles titles his most notable win was at the ATP Championships in Cincinnati (w/Mark Kratzmann, AUS).

Nicknamed “Killer”, he experienced chronic injuries throughout his career, having had more than 10 knee operations.

He grew up in a sporting family – his father was a renowned Australian Rules football coach.

After retiring from the Tour he later became Lleyton Hewitt’s coach and guided Hewitt to world No.1. Hewitt, at 20 years and eight months, was the youngest player to achieve the No.1 spot in the history of the ATP rankings.

After splitting with Hewitt, he began coaching American great Andre Agassi, helping him back to the No.1 position. Agassi achieved this feat in May 2003, making him the oldest player to claim the No.1 spot.

Cahill represented Australia in Davis Cup from 1988 to 1991 garnering a 6-4 win–loss record (2-4 singles, 4-0 doubles).

His highest singles ranking was No.22 in April 1989, and in doubles he peaked at No.10 in August 1989.

In 2007, Cahill was appointed to the position of Australian Davis Cup coach, which he resigned from in February 2009.

In March 2009 he joined the adidas Player Development Program.

He also commentates for ESPN and is now based in Las Vegas.