CCTV shows a drunk Jaydon Sienkiewicz, 21, leaning over and pinching the woman’s bottom.

A man, believed to be the woman’s boyfriend is seen furiously pushing her out of the way and up against a wall before lunging towards Mr Sienkiewicz and stabbing him.

While clubbers hold back the stabber, the tourist is seen walking away holding his chest before stumbling back to his table where his horrified dad found him covered in blood.

The incident took place on Thursday around 4am at the popular party hotspot Mixx Discotheque in South Pattaya.

The Bangkok Post reported Mr Sienkiewicz, understood to be from the western suburbs of Sydney, had been partying with a group of 10 people, including his Australian father and stepmother, when the stabbing took place.

His stepmother, Khumkhun Songnangrong, 33, reportedly told investigators they were having a “fun time” in the club and said she was not sure why anyone would stab her stepson.

She said she was horrified when he went to the bathroom and returned covered in blood.

Mr Sienkiewicz received a gift of 5000 baht ($AU205) from Thai authorities to go towards his treatment — despite him groping the woman.

Police lieutenant Sombat Kaewmumpung, deputy police inspector of Pattaya City Police, said: “We captured the scene before the incident.

“The injured man was drinking at the pub table then touched the woman’s bottom.

“It caused the offender to bring a knife out and stab him.”

Thai police are now using the CCTV footage to try to track down the knifeman as Mr Sienkiewicz recovers in a stable condition in hospital.

They have issued an arrest warrant for the unnamed attacker, who police say is a westerner who may have left the country on Thursday.

Lt Sombat added: “We have issued an arrest warrant for the attacker seen in the security camera footage and he will be prosecuted according to the law.”