“Each member of Toto played a part in bringing ‘Rosanna’ to fruition. Vocalist Bobby Kimball and guitarist Steve Lukather transposed the musical key so the verse and chorus could be traded between them as a duet,” (LouderSound). “(Keyboardists) Steve Porcaro and David Paich ironed out the keyboard solo at five o’clock in the morning. Late drummer Jeff Porcaro laid down a masterful shuffle inspired by John Bonham.
‘Jeff was really into Led Zeppelin,’ Lukather told Classic Rock, ‘and for ‘Rosanna’ he morphed ‘Fool In the Rain’ [from Zep’s 1979 album In Through The Out Door] with a Bernard Purdie drum groove [a renowned session drummer, Purdie invented the Purdie Shuffle]. And we took it from there.’ As former session musicians to a man, it was little surprise that Toto bottled ‘Rosanna’ fast in the studio. ‘In one afternoon we did the basic rhythm track,’ Lukather said. ‘And that first guitar solo was made up on the spot the first time we played it.'”
All the hard work certainly paid off: upon its release in the summer of 1982, the track reached US #2 and UK #12. Starting in G major, the key shifts down to F major for the second half of the verse. But the downward motion in key is muted by a rising melodic range (up a minor seventh) as the lead vocal shifts from Lukather to Kimball at 0:36.