Marc Leishman is heading into a three-man four-hole aggregate playoff against two major winners for the British Open at St Andrews.
The Victorian backed up a sensational third-round eight-under 64 with a lovely six-under 66 to surge to 15 under par for the tournament.
It left him tied with American former Masters winner Zach Johnson, who also shot 66, and 2010 St Andrews champion South African Louis Oosthuizen (69), sending the trio out for extra holes to decide the Claret Jug.
Oosthuizen and Johnson birdied the final hole to get their place while Leishman had a 20-foot chance to ultimately win outright, but missed on the left.
Jason Day has fallen one shot short, settling for a final-round 70 to be at 14 under, tied with Jordan Spieth whose grand slam tilt slipped away with a bogey on the 17th hole.
Both could have found a way into the playoff with birdies on the last but failed in their bid.
Spieth dumped his wedge approach into the Valley of Sin and just missed a putt from off the green while Day left a 25-foot downhill putt short and was shattered.
Three months after almost quitting golf to be a grieving fulltime father, as wife Audrey fought for her life in a Virginia Beach hospital, Leishman is a handful of holes from clearly the biggest win of his life.
Battling toxic shock syndrome, a life-threatening respiratory infection, Audrey was given less than five per cent chance of surviving and Leishman braced for the worst, missing the masters to be by her side.
But now he is bidding to become Australia’s first British Open champion since Greg Norman in 1993 and the first Australian to win at St Andrews since the late Kel Nagle in 1960.
Adam Scott evoked his British Open demons with another back nine collapse.
Scott took down the opening nine at the Old Course in five-under 31 and then birdied the 10th to jump to 15 under for the tournament, at the time joining the lead.
But he played his last five holes in five over par, making bogey on the 14th and then inexplicably missed a putt from one foot on the 15th.
Another bogey on the 17th and a double bogey to finish after driving the ball out of bounds saw him drop all the way back to 10 under.
Scott bogeyed the final four holes to cough up a four-shot lead in 2012 and was also inside the top five in 2013 and 2014 without claiming victory.
Marcus Fraser (-7), Steven Bowditch (-6), Matt Jones (-6), Geoff Ogilvy (-5), John Senden (-5), Scott Arnold (-5), Greg Chalmers (-3), Brett Rumford (E) round out the Australian tilt.