The moment Heather hit the dancefloor

His estranged wife managed to laugh it off and, more importantly, still impressed the judges.

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The tumble happened towards the end of Heather's routine.

The 39-year-old, who has a prosthetic left leg, fell during a samba routine with partner Jonathan Roberts on the US show last night.

It happened in the final movement when Mills put her leg on his chest. After lifting her right leg she lost her balance and collapsed to the dance floor.

Heather gathers her composure after sliding across the floor.

As Roberts helped her up she giggled and shook her head while the couple were treated to a round of applause from the audience.

Still smiling: Heather puts on a brave face.

Heather has spoken openly about the challenges of performing with a prosthetic leg.

Mills, who is embroiled in a bitter divorce battle with Sir Paul, was uninjured.

And despite her mistake she scored one of the highest marks of the night — 21 out of 30.

Heather still received praised from the judges.

Judge Carrie Anne Inaba praised her as a "free spirit". British judge Len Goodman described the dance as a "very good performance", while Bruno Tonioli, her biggest fan, said she was a "disco diva".

Earlier, film of the couple rehearsing showed Mills insisting on her 26-year-old partner having his chest hair removed — and Roberts grimacing in pain as it was waxed.

Heather's dance partner proves he's a true fan.