The Baggies left Anfield still searching for their first win of the season and Megson's tenuous grip on power at the Hawthorns slipped further when what started as a good-natured squirting of water in defender Thomas Gaardsoe's face soon erupted to a free-for-all on the coach back to the Midlands.
Megson said: "There was an incident on the team bus. I shall be trying to find out what happened.
"I’ve given the players the day off on Monday so they can clear their minds and gather their thoughts."