Michael Jackson, the self-styled King of Pop, is to release the most expensive album ever made in a desperate battle to regain his crown.

The eccentric singer is said to have spent $30m (about £20m) and five years recording Invincible, his first entirely new album in over a decade. He recorded 50 tracks before slashing the results and critics say that the 15 surviving songs mark an astonishing return to form that could revive Jackson's career.

Unwilling to take any chances, the singer has embarked on a promotional blitz in the run-up to its October release. Last night he appeared with his brothers in the Jackson Five for the first time since 1984 at the first of two modestly titled Tribute to Michael Jackson concerts at Madison Square Garden, New York City.

The star-studded audience was testament to the status he retains - Muhammad Ali, Sean Connery and Marlon Brando all agreed to attend - as was the line-up, which included Eminem and Destiny's Child.

Jackson is counting on such bright young things to rejuvenate his career. He called in the R&B producer Rodney Jerkins, known for his work with Mary J Blige and Jennifer Lopez, to produce Invincible.

The reclusive multi-millionaire has become more famous for his eccentric habits, which earned him the nickname Wacko Jacko, than his undoubted gifts. Now in his 40s and a father of two, his career has been on a downward slide since 1982 when his album Thriller stayed at number one for 37 weeks and sold an astonishing 24m copies.

His multi-million dollar settlement of child abuse allegations in 1993 seemed likely to kill off his career. But the former child star is attempting a coup on a par with Elvis Presley's '68 Comeback Special. Those TV shows electrified audiences and kickstarted the ailing career of the king of rock'n'roll, whose daughter Lisa Marie was later briefly married to Jackson.

"Invincible is the most important album of his career - a real maker or breaker," said Peter Robinson, pop critic for NME and the Face. "He's a fantastic pop star and it will be interesting to see how he develops. They're trying to surround him with all these people who are more relevant to young people."

The first single, You Rock My World, has surprised critics who expected a lightweight ballad along the lines of Jackson's last releases such as Earthsong. "It's his best work since Bad," enthused Robinson. "You forget that he does have a great voice and a really distinctive sound and that comes out on the record."

Robinson believes that a comeback is plausible. "In the 90s Madonna was in the dumper, making quite bad records, and that's been completely written out of her history," he pointed out.

"She managed to do it by choosing the right producers, although admittedly she was a bit more inventive than Jackson. He's still quite sharp. He recruited Rodney Jerkins a while back and was actually one of the first to recognise that he was an amazingly talented writer and producer."

"It's too early to write Jackson off," agreed Emma Jones, editor of Smash Hits, who says she was shocked by how good his new single was. "He's an enigma and the mystery that surrounds him makes him even more of a star. There's no one you can compare to him in the modern pop world.

"He's a great showman, a fantastic songwriter and his music has stood the test of time. People are going back to albums like Off the Wall and calling them classics. Young bands like 'NSync and the Backstreet Boys are saying how good he is."

Ajax Scott, editor of the record industry bible Music Week, is similarly impressed by the artist's new direction. "He's still got it," he said.

"Invincible doesn't just sound like they spent a huge amount of money on the latest producers. It sounds very much like Jackson, but contemporary Jackson."

But Scott says the star's place in history is assured whether the album soars or sinks without trace. "He's sold so many records and is such an icon that 'make or break' is not even a relevant concept, in a sense. Whatever happens won't alter his reputation as having fundamentally changed soul music."