By Agence France-Presse
The U-18s cup match (October 21) between Bangkok Sports Club and Satri Angthong had finished 2-2 in normal time, prompting an epic shootout that ended 20-19.
The bizarre penalty came early on, throwing Bangkok a lifeline in a shootout that Bangkok Sports Club had been on the verge of losing.
One of their players stepped up to take the third penalty knowing a miss would see his team dumped from the tournament.
He struck the ball hard onto the crossbar, sending his opposite number dashing from his line in jubilation.
But in comical scenes, Satri's keeper turned to see the ball bounce near the penalty spot and spin back towards the unguarded net.
He scrambled back as the ball crossed the goal line, sending him to his knees in despair.
"As the ball hit the bar, the penalty taker's face turned grey because he thought his miss had cost his team the game," said Apinun Prasertsang, a teacher at Bangkok Sports Club, a sports school in the Thai capital.
"But the ball bounced back into the goal as the Satri keeper was celebrating in joy." A video of the bizarre penalty has been viewed more than two million times on Facebook.