Guy Ritchie heaped praise on Madonna at the premiere of his new flick, RocknRolla, and said his wife would make an excellent nurse.

The Ray of Light star injected lead actor Gerard Butler, who was suffering from a cold, with a vitamin jab, so that he could attend the Leicester Square extravaganza.

With a face as serious as some of his gangster protagonists, Ritchie said: "She's very fluent in the medicinal world, so she knows, actually, more than most doctors I've met before."

The revelation may come as a surprise to many medics, who take an average length of 11-16 years to become qualified doctors.

Madonna's appearance in London shocked on-lookers, as her busy tour schedule, rumours of divorce and medical commitments led fans and press alike to believe she wouldn't make it.

But she arrived at the Odeon West End cinema just minutes before Ritchie's gangster film was shown.

RocknRolla is set in London's criminal underworld and features property scams and Russian mobsters.

Ritchie, 39, wrote and directed the film, which is seen as his make or break movie following his last two critical and commercial flops, Swept Away and Revolver.

He also revealed that he has already written the sequel, and said: "If people go and see this and like it I'll make the second one straight away."

The film's stars, Scottish heartthrob Butler and Thandie Newton, were the focus of the cameras and the screams before Madonna stole the show with her late appearance.

The pair, who characters are called Mr One-Two and Stella the accountant, provide the film's key love story.

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