On 9 July 1971, Humble Pie opened for Grand Funk Railroad at their historical Shea Stadium concert, an event that broke the Beatles record for fastest selling stadium concert, to that date. Also in 1971 Humble Pie released their most successful record to date "Rock On" as well as a live album recorded at the Fillmore East in New York entitled "Performance Rockin' the Fillmore". The live album reached No. 21 on the US "Billboard" 200 and was certified gold by the RIAA. "I Don't Need No Doctor" was a FM radio hit in the US peaking at No. 73 on the "Billboard" Hot 100, propelling the album up the charts. By the time of the album's release, Frampton had left the band, and went on to enjoy success as a solo artist.