Prime Minister Manmohan Singh, a reluctant birthday boy, turns 80 on Wednesday but will spend the day working as he has done in the past, officials said.
A workaholic, the Prime Minister has shied away from celebrations on his birthday but there have been occasions when he has cut a cake on board his special aircraft during foreign trips.
The Prime Minister will on Wednesday give away the Shanti Swarup Bhatnagar awards and Council for Scientific and Industrial Research (CSIR) awards on the organisation's 70th Foundation Day function.
The Prime Minister is the president of CSIR, whose foundation day coincides with his birthday.
"He will work as usual (on his birthday)," an official said.
Though some political leaders are expected to call on the Prime Minister to greet him, the celebrations will be a low key affair, the official said.
Born in 1932 in Gah Begal village in what is now Punjab province of present-day Pakistan, Manmohan Singh's birthday falls on Sep 26 because his parents had given it as his date of birth to get him admitted in school.
His family shifted to India during partition.
"Sep 26 is shown in the school records as my date of birth," Manmohan Singh had said when asked about it.
The Prime Minister has celebrated his birthday mid-air on four occasions.
He had cut a cake on his 77th birthday while on board Air India One enroute to Pittsburgh from Geneva and had also done so last year on his flight back from Frankfurt.
Singh won a place in the history books for lighting the fuse for the nation's rapid growth when as finance minister in 1991 he rescued an economy teetering on the brink of bankruptcy.
His reputation has taken a battering as premier -- especially since the 2009 re-election of the Congress government, with Time magazine branding him "The Underachiever" on its cover earlier this year.
But a sudden blitz of reforms designed to revive the sharply slowing economy has given his image a new boost with a newspaper proclaiming he has got his 'mojo back'.
Singh is widely expected to stand down at the next elections due to be held in 2014.
"In his last innings he would like to leave on a strong wicket," Deepak Lalwani, head of India-focused financial consultancy Lalcap in London, said, employing a cricketing metaphor.
Congratulations came from Indian politicians and Russian President Vladimir Putin on Tuesday sent birthday greetings, calling Singh an "outstanding statesman."
"You have earned well-deserved respect as an outstanding statesman and eminent economist," Putin said, also crediting him with broadening the Russia-India relationship.
India's ties with the United States have blossomed in recent years with a landmark nuclear deal offering New Delhi access to civilian atomic technology.