The day after Christmas in 1968, Led Zeppelin made its US concert debut as a late addition opening act for a concert headlined by Vanilla Fudge that also featured Spirit.   The show took place on at the Auditorium Arena in Denver.  Thomas MacCLUSKEY covered the show for the Rocky Mountain News, lauding Jimmy Page in his review as "exceptionally fine". He was a good deal less impressed by Robert Plant, judging him that night to be a singer "a cut above average" with "no special appeal in sound."  The concert took place about two weeks before the US release of the first Zeppelin album.