With the tie already in pocket, Yuki pushed India closer to a whitewash after he struggled past Jose Statham 2-6 7-5 7-6(5) in the fourth rubber, which lasted for two hours and 41 minutes under scorching sun.
Sanam, who had to wait for his turn until the last match, closed the tie in style with a dominating 6-4 6-1 win against Artem Sitak in one hour and 17 minutes.
Sanam's win was the first straight one for India in this tie as the other matches, except the second rubber, lasted full distance. Three wins on the first two days had already ensured that India will stay in Group I for 2013 competition.
The Kiwi team will fight it out with Chinese Taipei next month to retain its place in Group I. It's the first time since the 2005 tie against Uzbekistan that India have whitewashed an opponent in Davis Cup.
The youngsters have already been rewarded for their good show as AITA has said it will stick to them till India competes in the Asia/Ocenia Group zone.
Since Mahesh Bhupathi and Rohan Bopanna will not be considered for selection for close to two years, these youngsters will be India's face in the Davis Cup.
Sanam found himself in the pit several times in the first set, but managed to get out every time. He was quick on the court and had the sting in his shots.
The two players exchanged serves in sixth and seven games to be locked 3-3. A double fault by Sitak on a break point put Sanam ahead. The Indian was again in danger of losing the advantage but saved three breakpoints before pocketing the set. The second set completely belonged to Sanam.
Earlier, Yuki overcame a sluggish start to set India up for a rout. Yuki was far from convincing and it was his second Yuki was far from convincing and it was his second come-from-behind win as he had erased a two-set deficit in the opening singles.
Yuki also battled cramps towards the end but hung on to eke out a win. Many a times he was in advantageous position but could not deliver the knockout punch. At 40-0, he was up by three break points in the 12th game of the second set, but took two more to finally draw parity.
After failing to convert his first match point in the final set, he was up 5-0 in the match tie-break, but allowed Statham to take five points on the trot to make it 5-5. Yuki was slow off the blocks, struggling with his first serve.
After committing two double faults and netting a forehand, he was facing a breakpoint in the very first game. Yuki had his chances in game four but squandered two breakpoints. Unforced errors added to his struggle as he dropped his serve at love to hand 3-2 lead to Statham.
The youngster was even missing easy put-aways. Two more double faults coupled with unforced errors put Yuki down by another break and Statham found himself 5-2 ahead. Yuki saved two set points before conceding the lead in 37 minutes.
The Delhi lad improved slightly in the second set but still he was far from his best. The searing heat started to bother Statham as his movement slowed down. The set went on serve for 11 games, and Statham was serving to stay.
The Kiwi played his most inconsistent game of the match as three unforced errors put Yuki a point away from pushing the issue to the third set. However, the Indian youngster, at 40-0 on Statham's serve, squandered four set points before finally converting the fifth with a forehand winner.
The double fault came to haunt Yuki again as his sixth of the match handed his rival a chance to nose ahead in the decider. He saved it with a deft drop shot but sent a forehand long to let his rival go up 3-2. Statham was struggling to cope with the heat. His movement dropped and he was trying to keep the points short. Yuki, too, was struggling to move as he suffered cramps, which allowed the decider to go full distance.