Sinha won 6-7(10) 7-6(3) as Vardhan withdrew in the opening game of the final set.
Both players held their serve till 3-3 and Vishnu broke Nitin to take a 4-3 lead but the home favourite broke back immediately to level 4-4.
The set went on to tiebreak but Nitin had a double fault at 5-3 as Vishnu bounced back and eventually Vishnu won the tie break at 12-10.
In the second set Nitin broke in the first game and went on holding till Vishnu again broke at Nitin serving at 5-4.
Trailing 15-30 in the first game, Vishnu conceded the match.