Shortly thereafter, Cahill turned pro and quickly had success, winning the 1977 Australian PGA Championship.
In the ensuing years, however, citing personal problems and "poor practice habits," Cahill's game declined.
In 1980, however, Cahill renewed his relationship with former mentor Kevin Hartley and his game improved, culminating with a three wins in Western Australia in May 1982.
[10][11] In the late 1960s, Cahill graduated from Altona High School and started attending Footscray Technical College as an accounting major.
[16] Peg McMahon of The Age stated, "Cahill's phenomenal run of success is a record for Victorian golf."
"[18] After the event, Peter Stone of The Age wrote, "Potentially, Cahill could become one of Australia's great golfers.
[25][26] In 1975, the golfer Norman Von Nida began to serve as a mentor and supported Cahill's career.
[27] In March, based exclusively on a recommendation from von Nida, Cahill traveled to Europe to play on the European Tour.
[27] During his first three months in Europe, Cahill did not have much success; his only earnings were 120 pounds at the Madrid Open and he needed government assistance to get by.
The Australian PGA stated that Cahill was "ineligible" because he had not played for three full years as a "trainee professional."
During the European year, Cahill made the cut in the majority of his events but did not produce many high finishes, only recording one top-25.
[42] However, his primary competitors, Mike Ferguson and Bob Byman, self-imploded during the middle of the front nine, with several over-par holes.
[48] Due to the success, Trevor Grant of The Age wrote that Cahill was "the young Australian most likely to make the biggest impact on the international scene.
[57] In the final round, Cahill made "one of the strongest finishes" of the tournament with six birdies to record a four-under-par 68.
Late in the month, he began play at the Golden Gate Classic at Coolangatta & Tweed Heads Golf Club.
[60] Cahill stayed in contention for the remainder of the tournament and on the 72nd hole "sank a long putt" to enter a playoff with Somers.
"[63] The following day, Somers and Cahill had short putts to win on the first two playoff holes, respectively, but each missed.
However, on the third playoff hole of the day − and seventh overall − Cahill "made no mistake" making a short birdie putt for the victory.
[64] The following week Cahill was again in contention to win at the Joe Jansen New South Wales PGA Championship.
On the final hole, similar to the previous week, Cahill made a "splendid" 30-foot birdie putt to enter a sudden-death playoff.
[71] In August 1981, Cahill won the two-round Barham Open by one over Ian Stanley and Terry Gilmore.
[6] Early in the year, in February, Cahill closed with a 67 (–5) at the Tasmanian Open to finish joint second, one back.
On the final hole, Cahill "badly pulled" his drive but it fortuitously hit a car and bounced into the middle of the fairway.
[76] The following week, at the CIG−Channel 9 Nedlands Masters, Cahill was again in contention at the final hole, tied with John Clifford this time.
Cahill recorded top tens at the Resch's Pilsner Tweed Classic and Victorian PGA Championship.
[81][82] Due to his good play over the course of the year, Cahill was invited to represent Australia at the World Cup again.
[30] Late in the year, he told John Hourigan of The Canberra Times that there was simply "nothing to report" about his experience in Europe.
At the pro-am, Cahill shot a 71 at the "demanding composite course" to tie Tom Watson for medalist honors.
[92] The following week, at the U-Bix Classic, Cahill again played well at the pro-am, shooting a 66 to finish joint second, one back of Stewart Ginn.
[95] For the remainder of the decade, Cahill continued to struggle, only recording a couple top-tens in minor events.