Leishman moved nine places up the leaderboard at the Aronimink Country Club with five birdies against three bogeys on a soaked golf course.
American Keegan Bradley defeated 54-hole leader Justin Rose at the first hole of sudden death to claim the title but Rose still had a victory of sorts, ascending to the world Number One position with his runner-up result.
It was a dramatic final day in Philadelphia with several storylines unfolding aside from the tournament itself, among them Tiger Woods making a charge and Jordan Spieth failing to advance to East Lake for the first time since 2013.
For Australian fans it was Leishman’s battle to qualify for the season finale which took precedence and the Victorian delivered in style after a poor opening round had him in danger of missing out.
He will join Cameron Smith and Jason Day in the elite 30 player field in two weeks, the Tour taking a week off ahead of the season’s final tournament.
Adam Scott, the only other Australian to qualify for the play-offs, needed to finish sixth or better this week to earn his place in Atlanta but an opening 74 put paid to that and he ultimately ended his season with a T51.
We did it Dad.... World Number 1⃣ Thank you so much to my family, friends & everybody that has helped me achieve this incredible goal. Also, my sponsors @TaylorMadeGolf @adidasGolf @Hublot @Mastercard @ZurichNAnews @MorganStanley @LamkinGrips Thank you! #Team pic.twitter.com/geZgcpTR7U— Justin Rose (@JustinRose99) September 10, 2018
Day was the best of the Australians at Aronimink with a T24 result, Leishman’s T41 next best followed by Scott at T51 and Smith near the tail of the field.
The reigning Australian PGA champion was at less than his best all week but stellar play in the first two events of the play-offs had guaranteed his place in the Tour Championship.
He will begin the week in Atlanta 10thin the standings, two spots ahead of Day, while Leishman is 29th.
It was a dramatic final day in Philadelphia where players returned to the course early Monday morning after heavy rains forced the suspension of Sunday’s final round.
With the downpours continuing overnight there was speculation the tournament would be declared after 54 holes but officials were determined to get a result and an early start saw them achieve that goal.
Playing in groups of three off two tees and starting at 7.15am local time, it was a dramatic final round which saw Bradley claim an emotional first victory in six years.
The 2011 PGA champion has endured a difficult run in recent years but a final round 64 put the pressure squarely on Rose whose putt for par and outright victory at the final hole cruelly lipped out.
When he missed again at the first extra hole, this time from short range after again catching the edge of the hole, Bradley was back in the winners’ circle.
Justin Rose ... for the win ... pic.twitter.com/eRYqLVnCgS— PGA TOUR (@PGATOUR) September 10, 2018
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