Coletta had birdied the 71st hole to join Ledesma is a share of the lead at 14 under with one hole remaining and watched on as Ledesma holed from close to 30 feet on the last hole.
23-year-old Coletta had begun the day tied for the lead with Ledesma but immediately fell three shots behind after a devastating double bogey on the par-5 opening hole at TPC Colorado which 28-year-old Ledesma birdied.
Inexplicably, big-hitting Coletta also bogeyed the par-5 5th hole to fall further behind and seemingly out of the tournament.
But the Melbournian rallied with four birdies and no bogeys between the 6th and 17th holes, re-igniting hope of a PGA Tour promotion before the grandstand finish of Ledesma.
Coletta is projected to climb to 25th position on the Korn Ferry Tour’s points list with the top 25 players at the end of next month's WinCo Foods Portland Open awarded PGA Tour cards.
With the victory, Ledesma secured his ticket to the 2020 PGA Tour with only 4 events remaining before the Korn Ferry Tour’s 4-event Finals Series begins at the Nationwide Children's Hospital Championship in August.
Rhein Gibson was the next best Australian at the TPC Colorado Championship sharing 16th and is projected to move to 8th on the points list.
Jamie Arnold's PGA Tour hopes remain alive after sharing 19th to move up to 42nd on the projected points list and Brett Drewitt shared 33rd to move to 95th on the points list.
Victorian Cameron Percy was last of the Australians to make the cut, sharing 44th and dropping to 46th on the points list.
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