Mumbai: Sonu Nigam will undergo a knee surgery on June 7, a source close to the singer said. "Sonu will undergo a knee surgery on June 7 in Mumbai. He is fine... It's just a minor surgery," the source said. He is likely to undergo surgery on his left knee. If media reports are to be believed, it is because Sonu has been playing squash without proper guidance that he is having to undergo surgical treatment. Also, he is said to have cancelled all his music concerts till he recovers completely.