King had been expected to lead the line in South East London as the Golden Boys strove desperately for a first Premiership victory of the season, and his absence lead to terrace speculation that the 26-year-old Jamaican had fallen foul of old habits.
Stories varied from a possible incident in a night club, to a midweek bust up at the training ground, but a phlegmatic Boothroyd was quick to put the record straight immediately after the game.
"Marlon was missing today with a knee injury. After the Arsenal game he reported some swelling and so we sent him to see the medical team immediately.
They've advised that he should rest for five days and we'll re-assess it at that point. So he's at home resting up with his wife and daughter, which is a fully deserved break for him.
If people are going to ask me if that's it because we've lost last season's top scorer, then I'll tell them different.
Marlon is a great player but he is just one player here and we'd miss any of our players at any stage of this season."