He was originally with the group from 1978-1983 and sang on Eye Of The Tiger. He was brought back into the fold in 1993 and stayed until he was fired in 2000 and replaced by Jimi Jamison. He rejoined the Chicago outfit in 2013 with the band stating their intention to carry both Bickler and Jamison.

But following Jamison's death in 2014 from a heart attack, the band recruited Cameron Barton - and Bickler says, recently, he wasn't invited to take part in rehearsals or the group's live shows.

He exclusively tells TeamRock: "It was quite a shock when Jimi passed away. It was such a unique thing. I swore I would never go back but I got a call from guitarist Frankie Sullivan and he said, 'Would you like to come and sing with Jimi?'

"I leapt at that because I was a good friend of Jimi's. It was so sad, I didn't realise how bad his health was. Nothing really happened for a long time but Frankie said he still wanted it to be two singers and he was trying to find somebody - not to replace Jimi, but find someone to take his place."

Bickler reports the search went on for a number of months and once Barton was onboard, the band headed to Nashville for rehearsals. And that's when he sensed all wasn't well within the lineup.

The singer continues: "It was kinda strange for me because I didn't really know Cameron Barton. And after that it got stranger. I got the feeling they didn't want me but that they didn't want to say it - they wanted me to say it. They wanted me to withdraw, as Frankie put it. So I said no. Then I turned the conversation over to management.