Indian officials said Singh and Obama met briefly as the leaders of the Group of 20 leading economies hammered out strategies to deal with the global economic slowdown and the crisis in the 17-nation Eurozone.
The two leaders share an excellent bonhomie, with the 50-year-old President often turning to the 79-year-old economist-turned politician for advice on economic issues.
On the margins of the summit, Singh had bilateral meetings with German Chancellor Angela Merkel and the host country President Felipe Calderon.
The Prime Minister is also due to have meetings with Canadian and British Premiers Stephen Harper and David Cameron, French President Francois Hollande and Russian President Vladimir Putin.
It will be the first meeting between Singh and Hollande after the latter dethroned Nikolas Sarkozy in the recent Presidential elections.
As the current Chair of the five-nation BRICS bloc, Prime Minister Singh already has had interactions with the leaders of the grouping with whom he is not having any bilateral meetings.
They include Chinese President Hu Jintao and Putin. Besides India and China, the other members of the bloc are Brazil, Russia and South Africa.
After his engagements in this Mexican coastal resort town, Singh is due to travel to Brazilian city of Rio de Janeiro to attend the Rio plus Earth summit starting tomorrow.