Francis Rossi has spoken of his shock following the death of his Status Quo bandmate, Rick Parfitt, describing him as "the archetypal rock star".
The veteran musician suffered from a severe infection while in a Spanish hospital, which he had visited due to complications with a pre-existing shoulder injury, and died on Christmas Eve.
It followed years of concern about his ill health, which had seen him stricken by multiple heart attacks and a cancer scare.
Rossi said in a statement Parfitt was "one of the originals" who "never lost his joy, his mischievous edge and his penchant for living life at high speed, high volume, high risk".
He added: "Rick Parfitt had been a part of my story for 50 years. Without doubt the longest relationship of my life: this was also the most satisfying, frustrating, creative and fluid.
"From those early days, we worked together to create the Quo sound, look and hits. We spent years on the road, on the stage and in the studio, rarely far from each other, honing what we did.
"We were a team, a double act, a partnership and yet also two very different people, handling the pressures of growing older, constant touring, dealing with success and keeping the creative flame burning in different ways."
Rossi said his fellow veteran musician, who was 68 when he died, "developed his own sound, his own style" and casually inspired a generation of guitar players.
"Rick was the archetypal rock star, one of the originals, he never lost his joy, his mischievous edge and his penchant for living life at high speed, high volume, high risk," he added.
"His life was never boring, he was louder and faster and more carefree than the rest of us.
"There were any number of incidents along the way, times when he strayed into areas of true danger and yet still losing him now is still a shock.
"Even in a year that has claimed so many of our best, including now George Michael, Rick Parfitt stands out. I was not ready for this."
From 1967 onwards, Parfitt helped steer Status Quo into a role as one of the British rock scene's staple acts.
Hits such as Rockin' All Over The World became immortalised when they opened the historic Live Aid concert in 1985 - a performance broadcast globally.
In 2015, the band eventually passed a milestone enjoyed by only a handful of musicians, spending a total of 500 weeks in the UK album charts.
But despite international success, the Surrey-born musician's various vices caught up with him in 1997 when he had a quadruple bypass.
Despite doctors warning him he was on the verge of killing himself, he vowed not to become a "born-again Christian" and still enjoyed the "odd pint".
Parfitt became one of the latest in a long list of celebrated musicians to have died this year, with others including David Bowie, Prince, Leonard Cohen and the latest, George Michael.