Martinez also had words of praise for McManaman, who was at the centre of a fire-storm last month following a tackle on Newcastle's Massadio Haidara which, if it had brought a red card, would have ruled the Merseysider out of yesterday evening's game.
"Callum performs in the same manner in the playground with his mates or at Wembley in front of 62,000 people," Martinez said.
"Not many players have got that strength. Unfortunately he was in middle of storm, by being in the wrong place at the wrong time.
"During the international week, the only talk was about Callum McManaman. But he is someone you would pay for a ticket to watch.
"At a very young age he is potentially one of the biggest diamonds of English football."