It's week eleven and there's no room for mistakes as the remaining couples are back on the dance floor. It is a Strictly first as they perform one of two new dances - either a rock and roll or cheeky Charleston.The couples must pull out all the stops in a bid to secure a place in next week's quarter finals.The two couples with the lowest combined judges' scores and viewers' votes face the dreaded dance-off, with one couple hanging up their dancing shoes for good.Whilst they nervously wait for the result, the professional dancers perform a spectacular number.