Roberto Martinez felt referee Martin Atkinson got it very wrong in the second half of Everton's 1-1 draw with Liverpool on Sunday.
Reds midfielder Lucas Leiva had already received a yellow card when he fouled Ross Barkley with just over 15 minutes remaining in the 225th Merseyside derby.
Of the non-decision, Martinez was left scratching his head as to why the experienced match official did not act on the Lucas incident which could have influenced his team towards a victory at Goodison Park.
"I don't understand that decision. Lucas was very clever. His technical fouls were very clever but the second one was from behind and should have been given a yellow card," Martinez said.
"Martin has a clear view. We should have played against 10 men in the last 15 minutes."
Danny Ings opened the scoring for the Reds with a 41st-minute header from a James Milner corner before Romelu Lukaku pounced on a poor clearance from Emre Can to fire the Toffees back on level terms in stoppage time of the first half.