Lampard has called on the winger to grasp his opportunity in the Cup and give him a selection headache for the weekend trip to West Brom.
"We played Timo Werner out wide the other day, but the absolute natural winger who is fit at the minute is Callum.
"We know that in a Premier League squad with the number of games we're going to play, we need competition in those areas, back-ups in those areas and players competing to make that position their own.
"That's where Callum is at and that's why I keep saying he needs to train. He needs to show in training every day and when he gets his opportunity in games, which he will have in this game because he will play against Barnsley.
"He has to show in every minute, on and off the ball, what he can do for the team and at the minute, that's the position Callum is at. He's had an early breakthrough in his career because of his talent, he's had an injury and now I want to see him flourish again."