Delph said two-goal hero Agbonlahor proved how vital he is to the Villa cause with a scintillating performance at the Etihad Stadium.
"He summed his performance up with the two goals," he told Villa's website.
"There is not much I can say about Gabby - he is an outstanding player.
"He has been at the club a long time. He is a fans' hero and he is one of the big figures in the team.
"Nobody was happier for him than me - I was delighted for him."