Praise from Putin as Singh turns 80
India's Premier Manmohan Singh marked his 80th birthday on Wednesday working as usual as congratulatory messages arrived from home and overseas.
Singh, known as the father of India's economic reforms, was to spend the day quietly with his family, a spokesman said.
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.
Singh won a place in 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 the Economic Times 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," said Deepak Lalwani, head of India-focused financial consultancy Lalcap in London, employing a cricketing metaphor.
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.
But New Delhi and Moscow were on the same side of the fence during the Cold War and Russia is still India's largest arms supplier.
Singh was tapped to be premier in 2004 by party president Sonia Gandhi, widow of slain premier Rajiv Gandhi, after she led Congress to a surprise win.
Pundits believe the Italian-born Gandhi still calls the shots, taking on India's bruising political wheeler-dealers.
There are also cynics who say she opted for Singh because his self-effacing style meant he would not overshadow the Nehru-Gandhi dynasty which has given India three premiers.