Bollywood megastar Amitabh Bachchan is working on a new song he is set to lend his voice to for R Balki's upcoming movie Shamitabh."Oh and yes another session with Aadesh (Shrivastava) at his music studio last night did result in another song that I had to sing for ‘Shamitabh'...the finest quality of music from the genius of Ilayaraja, the magician from Chennai," Big B posted on his blog early Monday.Read Amitabh Bachchan to sport a new look in ShamitabhTalking of the veteran Illayaraja, Big B added: "How many years have passed since his emergence and how till today his prominence continues. The veteran, the master, who nurtured some very special musicians."Illayaraja has composed music for over 900 films in his career. Currently, he's busy composing for Shamitabh, which also stars Dhanush and marks the Bollywood debut of southern superstar actor Kamal Haasan's daughter Akshara.