Northants cricketer Ben Duckett poured a drink over a senior England player's head in the incident which led to him being suspended pending a disciplinary hearing, coach Trevor Bayliss has confirmed.
Duckett, a member of the Lions squad which met up with the full Test players preparing for the third Test at the WACA, was due to open the innings for an England XI on day one of the tour match against a Cricket Australia XI.
He was an unexpected absentee, however, and it emerged that the 23-year-old County batsman had been provisionally banned as he awaits the outcome of his hearing.
Asked to confirm reports that Duckett had poured a drink over a senior player - reported to be Jimmy Anderson - in a Perth bar, Bayliss nodded and replied: "I think that was the issue. It was boys being boys, I suppose, but totally unacceptable."
It is understood the issue arose between Thursday night and Friday morning, the first evening after England and Wales Cricket Board director Andrew Strauss agreed to a relaxing of a midnight curfew which was imposed two weeks ago.
That measure was taken in response to reports of Jonny Bairstow's 'headbutt' greeting for Cameron Bancroft - a playful prank from the Yorkshireman, also in a Perth bar on the first night of England's tour back in October.
It was an unfortunate gesture which came back to haunt England and their wicketkeeper, prompting Strauss to take action immediately after the first of two Test defeats so far which have left the tourists 2-0 down to Australia with three to play.
On the first night out after England's Test players returned to Perth, Duckett was out with some of them and his Lions colleagues - although it is not clear as yet whether any other members of either touring squad will face a disciplinary procedure.
Duckett is likely to discover the outcome of his hearing within 24 hours.
It is understood there was no police involvement in the incident, which also did not affect any members of the public.
The Telegraph is reporting that it was England pace bowler Anderson who Duckett poured the drink over, and that the incident happened in the The Venue in Perth, the same bar as where the Bairstow incident took place.
Duckett had been hoping to use the England XI fixture to catch the eye of the selectors, having falling out of the first team picture following four Tests as an opener in Bangladesh and India last winter.
Instead, he has made the headlines for all the wrong reasons.