With present "American Idol" winner Caleb Johnson implying in a recent interview that he is the first "real rocker" who won the show, David Cook reacts with a cover song from a legendary rock band icon.

According to Americanidolnet.com, Johnson did not directly addressed the comment to the former winner but stated that only Cook does the pop rock genre.

Johnson emphasized that past "American Idol" winners do more like "pop rock" or pieces that could even be categorized as "alternative" since there weren't any Led Zeppelin songs and the likes.

Johnson's opinion reached Cook and as a response, he made a rock cover of Led Zeppelin's "Rock 'n' Roll/ Whole Lotta Love" during one of his recent concert performances.

The performance certainly made it clear how big a rock star he was which Johnson did not see him to be.

"So, if you see that person... I guess let him know!" Cook added.

Yahoo Music wrote that Cook's response to Johnson's comments could spark a feud between the two, at least in the musical sense.

It's interesting to note that the two even appeared getting along well when Cook helped Caleb deliver his "Faithfully" act during the '80s week theme on "American Idol" Season 13.

Meanwhile, the most recent predictions about Johnson's debut album "Testify," involve breaking records but not in a good sense of the word. It might end up as the lowest selling album of an "American Idol" winner in the show's history.

Since its August 12 release, figures have been bad and getting it out faster than usual did not help achieve high sales.

His debut album's sales performance on its first week reached about 9k to 11k copies nationwide.

Others are saying that the artist is not as impressive when it comes to recording an album compared to live performances. It's never too late though, to change the way things go if Johnson would have more freedom to do his own stuff in future albums.

On the other hand, "American Idol" Season 7 winner David Cook took part in momentous music events like the 2014 Music Under The Stars Summer Concert Series and enjoyed his most recent European tour.

If first week album sales is any indication of "American Idol" triumph, then Johnson might have to take the backseat. Check out the first week album sales of other former "American Idol" winners including David Cook below.

Kelly Clarkson - Thankful - April 15 2003 - #1 - 297K
Ruben Studdard - Soulful - December 3 2003 - #1 - 417K
Fantasia Barrino - Free Yourself - November 23 2004 - #8 - 240K
Carrie Underwood - Some Hearts - November 15 2005 - #2 - 315K
Taylor Hicks - Taylor Hicks - December 12 2006 - #2 - 298K
Jordin Sparks - Jordin Sparks - November 20 2007 - #10 - 119K
David Cook - David Cook - November 18 2008 - #3 - 280K
Kris Allen - Kris Allen - November 17 2009 - #11 - 80K
Lee DeWyze - Live it Up - November 16 2010 - #19 - 39K
Scotty McCreery - Clear as Day - October 4 2011 - #1 - 197K
Phillip Phillips - TWFTSOTM - November 19 2012- #4 - 169K
Candice Glover - Music Speaks - February 18 2014 - #14 - 19K