Mitch Marsh was given out caught behind on day two of the second Test against India despite not nicking the ball.
Marsh did not review and appeared to start walking off before the umpire raised his finger.
Travis Head carried on to Australia's first century of the series on his home ground in Adelaide.
Mitch Marsh has upheld the vaunted spirit of cricket to a ridiculous degree, walking off on day two of the second Test against India despite completely missing the ball.
Ashwin turned to appeal to umpire Richard Illingworth, who did not react.
In the meantime, Marsh stepped away towards cover. Illingworth appeared to interpret that as the big West Australian admitting he nicked it, and the umpire raised his finger.
But Ashwin missed it, already turning back to look towards Pant and close fielders, ready to plead for a review from captain Rohit Sharma.
Head, meanwhile, meekly gestured for a batter's review, but Marsh had already turned and was walking off, without even considering a review or protesting the on-field decision in any way.
The Indians celebrated in a somewhat confused fashion, Ashwin seemingly unsure if Marsh touched the ball, as wicketkeeper Pant had barely moved to appeal.
"Even the Indians were questioning how was that out? … [Ashwin] was as surprised as anyone," former Australia fast bowler Glenn McGrath said on ABC Sport.
"[Marsh] took a step and that's prompted the umpire to give him out. And off he went.
"I think he'd be pretty dirty in the room now. He wouldn't be happy with himself."
Marnus Labuschagne told Channel Seven that the Australian team was "a bit perplexed" in the pavilion.
The odd circumstances became clear as replays showed a gap between bat and ball, and the "snicko" showed no spike, not even as the inside edge of Marsh's bat hit his pad.
"That's bizarre. I think that's missed," former Australia coach and player Darren Lehmann said in commentary for ABC Sport.
"He's just got confused there. You feel like you'd know you'd hit it, wouldn't you?
"It's just unbelievable, that."
The wicket in the 64th over left Australia teetering at 5-208, leading by just 28 runs.
But Head carried on to his eighth Test century at nearly a run a ball to power Australia into a dominant position.
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