`` Suddenly '' is a song from the soundtrack album Xanadu , and is the love theme from the 1980 film of the same name . The song is performed as a duet between Olivia Newton - John and Cliff Richard . It was written by John Farrar who also produced the record . It was released on Jet Records and reached No. 15 in the UK charts in October 1980 and reached No. 20 in the US . The video shows them in a penthouse singing the song to each other .

Question: who sang the song suddenly with olivia newton john
Answer: Cliff Richard