It's semi final week and the competition steps up a gear as the remaining three couples are one step closer to lifting that glitterball trophy. However, before they do, they must impress the judges and viewers at home.Hosts Bruce Forsyth and Tess Daly oversee proceedings as the couples perform two dances each. They take to the floor with a dramatic Argentine tango plus a ballroom or Latin dance.There are only two coveted places up for grabs in the final so everyone is pulling out the stops to secure their place.