David Cook plays Led Zeppelin after Caleb Johnson accuses him of 'not being a real rocker' (VIDEO)

David Cook has done his part in the Caleb Johnson publicity promo tour for Testify by responding to comments made by Caleb that the American Idol Season 7 winner wasn't a "real rocker".

In an interview with Yahoo Music, the American Idol Season 12 winner said that David Cook was was a pop-rock artist. "He never really did stuff like Zeppelin or Rush. He was more like... alternative," said Johnson.

David Cook got word of those remarks and in an encore performance in Indiana last Saturday he told the crowd:

"I read somewhere that somebody said that I wasn't really rock. I read that. So, we're going to do this next song in an attempt to prove him wrong. Because I would like to think that we are not any one thing!"

He then played a snippet of "Use Me" then continued with Led Zeppelin's "Rock 'N' Roll" and "Whole Lotta Love."

Caleb Johnson has yet to respond to the brewing feud between the two American Idol winners. His debut album Testify was released last week and is predicted to sell 9,000 copies on its first week, the lowest ever for an Idol winner, according to Hits Daily Double.

I'm glad David Cook is helping out with the publicity boost. Considering this is the most high-profile PR Caleb has had all week (even on a slow news weekend), he should be grateful.

Watch the video here: