Placido Domingo and Jose Carreras have led tributes to opera superstar Luciano Pavarotti, who has died aged 71.
The singer died at his home in Modena, northern Italy, after being diagnosed with pancreatic cancer in 2006.
"I always admired the God-given glory of his voice," said Domingo, who performed with Pavarotti in Three Tenors concerts for more than 10 years.
Jose Carreras, the third tenor in the trio, called him "one of the most important tenors of all time".
Pavarotti's body is now lying in state in the cathedral in Modena until his funeral on Saturday afternoon.
'Very good friend'
Spanish star Domingo remembered "that unmistakable special timbre from the bottom up to the very top of the tenor range".
"I also loved his wonderful sense of humour," he said.
"On several occasions of our Three Tenors concerts, we had trouble remembering we were giving a concert before a paying audience, because we had so much fun ourselves."
Fellow Spaniard Carreras told reporters: "We have to remember him as the great artist that he was, the man with such a wonderful charismatic personality - a very good friend and a great poker player."
Milan's La Scala theatre - where Pavarotti appeared 140 times - held a minute's silence for the star on Thursday, following the news of his death.
Dame Joan Sutherland, who performed with Pavarotti as his career took off in the 1960s, said he was a "great joy" to work with.
"It was incredible to stand next to him and sing along," she told BBC Radio 4's Today programme.
"The quality of the sound was so different. You knew immediately it was Luciano who was singing."
Conductor Zubin Mehta, who directed Pavarotti in Three Tenors concerts in Rome and Los Angeles, said: "The whole world will be listening today to his voice on every radio and television station.
"And that will continue. And that is his legacy. He will never stop."
Pavarotti also performed alongside a range of pop stars at his charity concerts.
Sir Elton John said it was "a sad day for music, and a sad day for the world".
Sting said: "We lost a great friend, a great voice and the world is a smaller place without the big man."
U2 singer Bono described Pavarotti as "a great volcano of a man who sang fire, but spilled over with a love of life in all its complexity".
"I spoke to him last week," he said. "The voice that was louder than any rock band was a whisper. Still he communicated his love. Full of love."
Queen guitarist Brian May said the world was "a sadder place, for the loss of this gentle giant".
British tenor Russell Watson said he was "privileged" to have performed with Pavarotti in London in 2001.
"He was very flamboyant, a true artist, but a very generous man," he told BBC One's Breakfast.
"His records always sounded fantastic. But unless you saw him live, there wasn't a full appreciation of how cavernous and incredible his top line was."
Welsh opera star Bryn Terfel described Pavarotti as "a truly inspirational and awe inspiring artist with a voice of pure gold".
"His premiership voice put us all into the second division," he said.
Soprano Lesley Garrett said Pavarotti's passing was "an enormous loss, not just for the world of opera, but for the world at large".
"He was a man of the people, and above all of us, he was determined to bring opera and great singing to a wider audience," she said.
Pavarotti last performed at London's Royal Opera House in Tosca in January 2002, despite his mother dying a few days before the first night.
Chief executive Tony Hall recalled: "He went back to take care of the funeral arrangements, then he came back for the first night here.
"When he took his curtain call, the applause went on for seven or eight minutes. I've never seen anyone bow so low or for so long, such was the emotion on that occasion. The audience absolutely loved him."
Former Royal Opera House general director Sir Jeremy Isaacs said: "He sang marvellously. He had this open, clear, natural, brilliant, piercing, ringing, thrilling, voice.
"He acted with his voice. He couldn't act for toffee with his person, but the music did it for him, and in that sense he was one of the most thoughtful of singers.
"Because he sang so elegantly, when he really let go, the hair stood up on the back of your neck."