India on Sunday stamp their authority over Uzbekistan by winning the Davis Cup tie 4-1 to advance to the World Group Play-offs.
Ramanathan beat Sanjar Fayziev in straight sets in the first reverse singles to hand India a 4-0 lead in the tie.
Ramanathan won 6-3, 6-2 against his 22-year-old Uzbek opponent in a match which lasted for around an hour.
Later in the day, Temur Ismailov, however, defeated Prajnesh 7-5, 6-3 in around 70 minutes to clinch a consolation win for the visitors.
India have now qualified for the Davis World Group Play-off which they will play at home in September.
The Indians had already won the five-match tie when Rohan Bopanna and Sriram Balaji defeated Farrukh Dustov and Fayziev 6-2, 6-4, 6-1 in the doubles match on Saturday to hand them an unassailable 3-0 lead.
Ramanathan and Prajnesh had won their respective singles matches to give India a 2-0 lead on the opening day of the tie on Friday.
Ramanathan had defeated Ismailov 6-2, 5-7, 6-2, 7-5 in the opening match of the tie before Prajnesh enjoyed an excellent Davis Cup debut with a 7-5, 3-6, 6-3, 6-4 win over Fayziev.
"We already had a 3-0 lead. It was good for me as I had no nerves today," Ramanathan said after his match.
"I played much better today, throwing a lot of first serves and playing the way I want to."
Ramanathan enjoyed an excellent start to Sunday's contest against Fayziev when he broke the Uzbek's serve in the second game of the opening set.
Fayziev had conceded the first two points through unforced errors and then with an excellent return of serve Ramanathan earned three break points.
Fayziev saved one break point with a big first serve followed by excellent placement before reducing the gap to 30-40 with a couple of excellent placements.
The Indian, however, won the next point to earn the break and take a 2-0 lead in the first set. Ramanathan then held his serve at love to go 3-0 up.
Fayziev had a chance to earn a break of his own in the fifth game when he put pressure on Ramanathan's serve. But the Indian did well to utilise his powerful serves and some superb forehand returns to hold serve.
The issue went with the serve before Ramanathan went on to win the first set in 37 minutes.
Ramanathan enjoyed a strong start to the second set as well, breaking his opponent in the very first game.
The next five games went with the serve before some excellent returns by Ramanathan and a few unforced errors by Fayziev earned the Indian his second break of the set.
The Chennai lad then held serve with ease to wrap up the second set and the match.
In the second reverse singles, Temur used his superior experience to good effect against Davis Cup debutant Prajnesh.
The contest was marked by powerful serves and ground strokes with both players consistently serving at more 200 km per hour.
"I wanted my team to have a victory, even in one game," Temur said.
"The conditions here are difficult. It is hot. Back home, we were playing in 20 degrees (celcius) and it is 35 degrees here." he added.
The first six games of the opening set went with the serve before the Indian had a good chance to earn a service break when three double faults by Temur took the game to 40-40.
Prajnesh had managed to put the Uzbek out of position with some superb ground strokes, but then hit his return long to hand his opponent the advantage. He then hit the net to enable Temur to hold serve.
That was to prove costly for Prajnesh as Temur broke his service in the 12th game of the set.
The Chennai lad had only himself to blame as three consecutive unforced errors saw him struggling at 0-40. He saved one break point with a powerful smash but then powered his return into the stands to hand his opponent the game and the set.
An upbeat Temur continued the momentum and wrested the early advantage in the second set when he clinched a service break in the second game.
The Uzbek led 0-15 with an excellent down the line return before another superb return by the Uzbek forced Prajnesh to hit into the net. Prajnesh then conceeded an unforced error to hand a break point to his opponent.
Another wide return by Prajnesh gave the break to the Uzbek, who took a 2-0 lead in the second set.
Prajnesh almost broke Temur's serve a couple of games later.
Temur had hit his return wide to give the Indian a whiff of a chance at 40-30. Prajnesh drew level at 40-40 with a superb placement that drew Temur wide before producing a powerful return to take the point.
Temur, however, came up with a nice accute angle volley to earn a point before Prajnesh hit the net to enable the Uzbek to hold serve.
That was the last bit of meaningful action that Prajnesh could conjure up as Temur went on to clinch the issue.
(With inputs from IANS)