British singer Sarah Brightman and leading Chinese singer Liu Huan will sing the main theme song for the Olympic Games at the opening ceremony Friday.Although the name of the song is being kept secret, it is the most hotly awaited show on the planet right now. The opening ceremony, helmed by top Chinese director Zhang Yimou, will focus on the long history and culture of the Chinese people. Performances will start at 5:45 p.m. local time, with the formal ceremony beginning at 7 p.m. The show runs until 11:45 p.m, said the Beijing Organizing Committee of the 29th Olympic Games (BOCOG). Nearly 91,000 people will watch the opening at the Bird’s Nest, with billions more expected to tune in worldwide to watch the extravaganza.