If you look at the 1940s, 1950s and 1960s Tamil movie scenes, T. M. Soundararajan (TMS) was the top male singer, singing a reported 10,138 songs from 3,162 films and over 11 different languages. Image source: Wikipedia
However, when Maestro Ilayaraaja came into the Tamil movie industry, TMS was not keen to sing for him. Apparently, he did not think highly of this “new” music director. If not mistaken, he only sang about 7 songs for the maestro so it is rather rare to find TMS singing for Ilaiyaraaja’s composition.