The Addicks, who sacked manager Phil Parkinson in the week, managed to get to half-time unscathed, but second-half goals from Andros Townsend and Jermain Defoe (2) sent the Premier League club through.
"I'm proud of the way the players performed," Peacock said. "As soon as I saw who was coming on the pitch at half-time, I thought we would have a problem.
"You love watching him on the ball, but not when you are playing against him.
"The little pieces I've seen of him, and what I saw in this game, he is right up there with the best."