Chennai: Lyricist Madhan Karky, who has penned the song that actor-filmmaker Kamal Haasan has sung for upcoming Tamil film "Avam", says the experience of having the superstar croon to his lyrics is "unforgettable".

"Had a super recording session with Kamal sir. A song for #Avam directed by Vijaykumar & music by Sundaramurthy. An unforgettable experience to watch and hear Kamal sir breathe life into my lyrics (sic)," Madhan tweeted Saturday.