Overview:The semi finals arrive, along with the nail-biting tension associated with another round of live performances. The remaining contestants must once master their nerves and take to the stage to determine whether the tutelage they've received at the hands of Will.i.am, Ricky Wilson, Paloma Faith and Boy George has paid off. As was the case last week, the identities of those would-be stars progressing through to the grand final will be decided by the viewers at home, who are encouraged to take part in a public vote to determine which act will leaving the contest.