Following his 2007 retirement from touring after being diagnosed with Lou Gehrig's disease, Toto bassist Mike Porcaro died in March while Yes bassist Chris Squire passed away on June 27 from leukemia.

When the tour was first announced, Lukather declared Yes as the group's musical heroes and the pairing a "crazy dream come true", and now says the losses have only served to further strengthen the personal bond and mutual respect between the two bands.

Lukather tells Ultimate Classic Rock: "There's a greater connection there than people realise. We've worked together in various configurations. And then both of us have suffered a tragic loss at the same time - we lost Mike Porcaro and they lost Chris Squire, sadly. He was a hero of mine.