Four of her children on a stage inspired by the grid of Manhattan, 80 tons of production equipment, more than 40 songs and a "time machine" - Madonna's career-spanning tour kicks off on Saturday after it was postponed due to illness.

The pop superstar begins her 78-show "Madonna: The Celebration Tour", marking her more than 40 years of hits, at London's O2 arena, three months later after its original July start date in Vancouver was pushed back when the "Vogue" singer was hospitalized in intensive care for a serious bacterial infection.

After taking time to recover, the seven-time Grammy Award winner has rescheduled most of the tour's North American leg to start in December after her European concerts.

In an interview with Britain's BBC published on Thursday, Madonna's musical director said the delay had allowed her to refine the show.

"Madonna has very high expectations of how much hard work people will put into something. It's very uncompromising - but she's equally as hard on herself," Stuart Price said, adding the singer had made a full recovery.

"So when she took a break, that pause created an opportunity to further enhance the show. And I'm sure the opportunity (for her) to focus on being 100% well was greatly received as well."

Tour organisers said Madonna would perform on "4,400 square ft. of stage, the largest for any Madonna tour", which nods to the grid of Manhattan. Madonna, 65, began her hugely successful music career in New York.

She will have 24 onstage performers, four of her children will also be on stage, and she will transported high up around the arena "in an illuminated portal frame that acts as a time machine". The O2 has also created a bespoke "Madonna themed Royal Standard flag", made by the British royal family's flagmakers to fly at the arena.

"The person that is going to take the stage looks incredible, sounds incredible, performs incredible," Price told the BBC, who quoted him as saying the concerts will feature more than 40 Madonna songs, with over half performed in full.

Madonna has shared pictures from rehearsals on social media. On Thursday she posted a blurred photo of herself with the caption "2 more days…………… #madonnacelebrationtour" alongside a party-popper emoji.

(Reporting by Marie-Louise Gumuchian; Editing by Alison Williams)