Manager Chris Coleman has warned the youngster he will have to continue to bide his time as Cole's understudy despite his third goal of the season.
He said: "Coley is our main man up front, so Collins has had to play wide-right at times this season.
"He wants to play up front and throws his toys out the pram on occasion like every player. At the same time, he knows what we expect of him.
"He is an exciting talent and has time on his side. He has that arrogance about him, which is a good thing, but it has to be tempered with a knowledge of what is good for the team."
John made an immediate impact at Derby after coming on in the 69th minute with Fulham trailing to Marcus Tudgay's goal. Moments after his arrival, John latched onto a long ball from Mark Pembridge to equalise.
He celebrated by revealing a message 'For You Mum' scribbled on his vest but Coleman won't be disciplining him for the yellow card. "He is young, hungry and still learning. That's what happens when you put young lads in the team," he said.
Coleman says it is unlikely he will be making a last-ditch attempt to sign left-back Michael Ball from Rangers today after missing out on Manchester City's Ben Thatcher.
He said: "I don't think there is enough time to sign anyone else. We wanted Ben and haven't done our homework on other players."
