The dance duo were in rehearsals for tonight's show (May 7) when Kai Widdrington accidentally kicked his partner Natalia Jeved in the head.
© ITV / THAMES/SYCO
"Natalia has had an ice pack on her head for the last hour and is hoping to be okay for tonight's show," a source told Digital Spy.
The insider added that Widdrington was "mortified" about the accident.
Producers are reportedly concerned that she may have suffered a concussion during the accident.
Kai and Natalia will perform their routine during tonight's second live semi-final alongside the likes of 14-year-old singer Paige Turley and street dancers Karizma Krew.
Ashleigh & Pudsey and Only Boys Aloud were the first acts to make it through to the final last night.
The Britain's Got Talent semi-finals continue tonight at 7.30pm on ITV1.
