India's 2nd Test in Kanpur fetched them number one ranking.
India would have lost number one ranking if Sri Lanka had won Kanpur Test.
By winning Mumbai Test, India have won series 2-0, the team will be number one till December 30th. December 30th is when the 2nd Test between South Africa and England gets over. And then also the only India lose the number one ranking if South Africa win both the first 2 Tests.Mumbai Test win has got Team India at the top of the Test rankings table on Sunday. Here are the permutations and combinations of the numero uno position: