One of Deep Purple's four indispensable albums (the others being In Rock, Machine Head, and Burn), 1971's Fireball saw the band broadening out from the no-holds-barred hard rock direction of the previous year's cacophonous In Rock.

Metal machine noises introduced the sizzling title track -- an unusually compact but explosively tight group effort on which Jon Lord's organ truly shined.

The somewhat tiring repetitions of "No No No" actually threatened to drop the ball next, but the fantastic single "Strange Kind of Woman" nimbly caught and set it rolling again, just in time for the innuendo-encrusted hilarity of "Anyone's Daughter," featuring one of singer Ian Gillan's first (and still best) humorous storylines to go with one of guitarist Ritchie Blackmore's most uncharacteristic, bluesiest performances ever.

"The Mule" opened the vinyl album's second side with what is perhaps Purple's finest instrumental, and on the hyper-extended "Fools," the bandmembers proved they could flirt with progressive rock without plunging off its cliff (although the song could probably have done without its drawn-out middle section).

And closing the album was the exceptional "No One Came," where intertwining instrumental lines locked together beautifully, Gillan wove another entertaining yarn that was part autobiography and part Monty Python, and the often underrated skills of drummer Ian Paice helped the song sound so unreservedly fresh and intuitive that one could almost be convinced the band had winged it on the spot.

Sure, the following year's Machine Head would provide Deep Purple with their commercial peak, but on Fireball, the formidable quintet was already firing on all cylinders.