Ramanathan outplayed Tearney in straight sets 7-5, 6-1, 6-0 to seal the match for the hosts at the Balewadi Sports Complex here.
The first set was evenly contested but it was the Indian player who proved superior and defeated the Kiwi 7-5.
The second and third games witnessed Ramanathan at his best. He outclassed his opponent in every department of the game.
Later in the day, Yuki Bhambri plays the second reverse singles match of the dead rubber with Jose Statham.
Earlier, Bhambri and Ramanathan both won their men’s singles matches to give India a crucial 2-0 lead against the visitors before Leander Paes and Vishnu Vardhan went down in the third rubber to Artem Sitak and Michael Venus.
Following the win, India will now take on Uzbekistan in the second round of the Asia-Oceania Group I in April.