The following incident occurred during an AFC Asian Champions League quarterfinal first-leg match between Foolad Sepahan (Iran) and Al Ahli (Saudi Arabia) on 20 September 2012. The match finished 0—0.
In the 64', away team Al Ahli won a corner kick and home supporters threw objects on to the pitch near the corner flag. After the corner was taken and the ball was out of play, AR2 Chow Chun-kit (Hong Kong) signalled that there was debris in his area. Referee Liu Kwok-man (Hong Kong) went to investigate. Videos of the incident show what happened:
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Firecracker Explosion in Iran (YouTube)
Referee Liu was responsive and responsible. As the match Referee he is empowered to stop, suspend or abandon the match as he sees fit. Eventually, the match was suspended for about five minutes and then play resumed. The AFC is now investigating the incident.