The two stars clashed at the Chateau Marmont Hotel in Los Angeles on Saturday night (24Apr10), with Jones allegedly landing a punch on the Clash of the Titans actor.
Now it appears Jones didn't emerge from the scuffle unscathed - a photograph of the Snatch star in L.A. on Sunday (25Apr10) shows him with red marks and scratches to his left cheek and the side of his neck.
The pair reportedly clashed after a long-running feud, which was sparked by an argument between the two men late last year (09), boiled over.
A report in Britain's Daily Mirror newspaper alleges Jones lashed out when the actor offered to shake hands on Saturday - prompting Hassan to aim a headbutt at Jones.
The brawl was eventually broken up by American Psycho actor Justin Theroux.
A source tells the publication, "It was like something out of a wild west film. Fists were flying and at one point the two of them were grappling on the floor. If they hadn't been pulled apart God knows when it would have stopped. There was a lot of shouting and swearing. It was bizarre."