Malaysian born, Taiwan-based singer Gary Cao and Hong Kong artiste Justin Lo are normally the best of friends. But the two pop stars turned into the worst of enemies during a roadside brawl after drinks at a pub here on Tuesday night.

The local paparazzi were rewarded with dramatic photos of Gary and Justin  punching each other and Gary kicking Justin while the latter was in the back seat of a taxi.

Justin Lo, better known as Zak Tin, was even invited as the guest singer at Gary Cao's concert in Malaysia last year.

On Tuesday night, they had gone for a drink at a pub with several friends at Central district. At about 1am, Gary left the pub in anger while Justin followed with a 'red face'. They then had a heated argument by the roadside. Hong Kong's Oriental Daily News reported that Gary punched Justin until he collapsed on the side of the road.

Justin got up and fought back. After a while, they were pulled apart by their friends. In a dramatic turn of events, the duo left in a taxi together with two male friends but the vehicle made an emergency stop soon after.

Gary alighted and was seen jumping on the street and calling out to Justin to step out for a one-on-one fight. The latter refused. The 30-year-old Malaysian then kicked at Justin who was in the back seat. After a while, the 33-year-old Lo got off and was seen grimacing in pain, using his hands to cover his groin.

Then Gary grabbed a road sign and attempted to hit Justin with it, but was stopped by their friends.

Half-an-hour later, both of them left separately accompanied by friends. Gary behaved as though nothing had happened during an interview with a Hong Kong radio station on Wednesday. He only talked about his concert in November.

At a press conference in Hong Kong on Thursday night though, Gary apologized to Justin for his act. 'I have no excuses, no reasons. I am wrong. I am willing to take whatever responsibility, punishment....Justin had never wanted to hurt me with his actions. It is very obvious this is not a fight ... it was me who lost control,' he said.