Madonna was recording with Katy Perry in the studio just hours before her collapse.

The 64-year-old star had been keeping up a gruelling schedule of 12-hour days for rehearsals for her 84-date 'Celebration' tour, along with working with Katy on a special project to mark her decades in the business, before she was rushed to hospital last weekend.

A source told The Sun newspaper's Bizarre column: "Madonna has long admired Katy and they have worked together before but never managed to actually put anything out.

"Madonna has been working around the clock to make sure both her music and her world tour are second to none.

"Obviously everything has been put on hold now but the fact she was in the studio with Katy just hours before being rushed to the ICU shows how determined she was to push ahead despite feeling unwell."

Madonna was reportedly intubated in intensive care after being rushed to hospital with a "serious bacterial infection" but has now returned home, where she is recovering.

Her 'Celebration' tour was due to kick off in Vancouver, Canada in two weeks time but, according to her manager Guy Oseary, all of her work commitments have now been cancelled.

He added: "Her health is improving, however she is still under medical care. A full recovery is expected."

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Source: Bang