A video released on Thursday showed Michael Jackson vigorously practicing a song-and-dance routine days before his death, supporting accounts he had been in good health.
In footage obtained by AFP, the pop legend performed at the Staples Center in Los Angeles on June 23, two days before he died, as he prepared for a 50-date set in London starting in July.
Jackson, while thin, is seen dancing with energy in a tightly choreographed sequence with a group of performers. Jackson sings on a headset and at one point pushes back his jacket to reveal his red shirt underneath.
In the footage, Jackson switches sharply in styles in a medley of some of his hits. The video starts with Jackson dancing wildly in front of a rock 'n' roll guitarist before a pause for dramatic effect.
Jackson then shifts to a snippet of "Billie Jean," one of his greatest hits, before singing, "They Don't Care About Us," one of his most controversial tracks in which he brought in a hip-hop influence.
The set ends with a sample of a car horn. The stage then fades to black as an outside voice instructs, "Hold for applause."
Associates of Jackson have described the 50-year-old pop star as being in good form, including at another rehearsal just hours before his death.
Jackson collapsed and died on June 25 at his rented Los Angeles mansion. Speculation has focused on whether Jackson was taking painkillers or other medication.
Jackson's voice coach Dorian Holley said Jackson was in an upbeat mood in the days before his death, joking around with his wardrobe and makeup staff.
"My friends call and ask, 'Was Michael sick? Was he weak? Was he ill?' It's the absolute opposite of that," Holley told CNN.
"He was very energetic, he was happy. He was even more playful than he normally was at rehearsal," he said. Holley said Jackson, 50, did not show his age.
"I'm sure that he was in pain after some rehearsals. But I got to tell you something -- the guys and girls dancing with him were all in their 20s," he said.
"When Michael was on stage with them, there was only one person that you could watch and that was Michael Jackson," he said.
A similar account came from Kevin Mazur, who was attending the rehearsal sessions as a photographer. "He was like an expectant father pacing up and down the stage," Mazur told Britain's Sun tabloid.
"He was just so focused. Between songs, he burst into laughter and joked around with his dancers and the director. I have never seen him so happy," Mazur said.
Jackson had planned a series of concerts at London's O2 Arena starting on July 13, part of a comeback for the King of Pop whose personal and financial life had sharply deteriorated in the past decade.
Concert promoters AEG Live, who released the video, are offering full ticket refunds for the concerts. British media reports said about 50 million pounds (59 million euros, 83 million dollars) has been spent on 750,000 tickets.