LONDON: Fans of Britney Spears are worried about her health again after she collapsed during a recent rehearsal on the European leg of her Circus world tour.

The Toxic hitmaker was practising a dance routine for a new song when she keeled over, suffering a bruise to her chest.

“She collapsed when the dancers went to put her back on her feet. She fell to the floor and landed on one of the dancers’ legs,” said a source. “The dancer’s tennis shoe smacked Britney in the chest and on the face. It hit her chest with such a force that it caused a four-inch bruise.”

It was reported Britney’s hectic schedule and a low blood-sugar level were responsible for the incident.