London, Dec. 26: The world of pop music was in a state of shock today following the sudden death of George Michael, apparently from heart failure, at the age of only 53.

As one of the duo of Wham!, the band he had formed with his school friend Andrew Ridgeley in 1981, Michael defined 1980s pop.

Referring to Michael by his family nickname of "Yog" (Yours Only George), Ridgeley tweeted: "Heartbroken at the loss of my beloved friend Yog. Me, his loved ones, his friends, the world of music, the world at large. 4ever loved."

Michael was found dead just before 2pm on Christmas Day by ambulance staff called to his home in Goring-on-Thames, Oxfordshire, with police later saying his death was "unexplained but not suspicious". Michael's manager, Michael Lippman, said he had died of heart failure.

His successes with Wham! included Wake Me Up Before You Go Go, Freedom, I'm Your Man, The Edge of Heaven and Last Christmas. Michael turned solo artist in 1986, selling in all 100 million albums with 11 UK No.1s in a career spanning four decades.

The pop pin-up once admitted that in his younger days, the figure adored by thousands of screaming fans was just a kind of alter ego he sent out on stage to do a job.

He fought hard to be accepted as a serious singer-songwriter and record producer, and successfully adapted his style to suit a more mature audience, all the while struggling with depression and doubts over his sexuality.

Those who attempted to assess Michael's legacy today said he would be remembered for his music rather than his troubled life, which included episodes with drink and drugs. In a tribute, Duran Duran referred to the so-called curse of 2016 - following the deaths of David Bowie, Prince and Rick Parfitt - posting on their official Twitter account: "2016 - loss of another talented soul."

Madonna posted on Twitter and Instagram a 1989 video of herself presenting Michael with an award, and wrote: "Farewell my friend! Another Great Artist leaves us."

Michael's collaboration with other artists produced such hits as I Knew You Were Waiting For Me (with Aretha Franklin), Don't Let the Sun Go Down on Me (with Elton John) and Five Live EP (with Queen and Lisa Stansfield). Among his biggest successes were Careless Whisper and Fastlove.

Michael spent most of 1987 writing and recording his first solo album, Faith, which was released in the autumn of that year and went to the top of both the UK and US charts, selling more than 25 million copies and winning a Grammy in 1989.

The first single from the album, I Want Your Sex, caused some controversy, particularly on US radio stations. Many refused to play it at all while others played a version substituting the word "love" for "sex". The single reached the top three on both sides of the Atlantic.

Michael was born Georgios Kyriacos Panayiotou in north London on June 25, 1963. His father was a Greek Cypriot restaurateur who had come to the UK in the 1950s, while his mother was an English dancer.

After years of refusing to be drawn on speculation about his sexuality, it was almost with a sense of relief that Michael disclosed he was gay in 1998 after he was arrested in a Beverley Hills public toilet in California by an undercover police officer and charged with a lewd act.

He was fined and sentenced to 80 hours of community service. The incident finally persuaded him to go public about his sexuality and his relationship with Kenny Goss, a Dallas-based businessman. He became a fervent support of LGBT issues, with some of his most famous solo work referencing his sexuality.

While playing a concert in Rio on his Cover to Cover tour in 1991, he met Anselmo Feleppa, the man who would become his partner, although Michael still did not publicly state that he was gay. Their relationship was to be short-lived as Feleppa died of a brain haemorrhage in 1993.

He gave few interviews, but when he did he was painfully honest. "I never had a moral problem with being gay," he later said. "I thought I had fallen in love with a woman a couple of times. Then I fell in love with a man, and realised that none of those things had been love."

He also acknowledged in an interview that he had had a very depressing time after he lost Feleppa to HIV.

"I had my very first relationship at 27 because I really had not actually come to terms with my sexuality until I was 24. I lost my partner to HIV... it took about three years to grieve; then after that I lost my mother (to cancer). I felt almost like I was cursed."

In November 1994, Michael released the single, Jesus to a Child, a tribute to his dead lover, Feleppa. It went straight to No. 1 in the UK.