India faced relegation to the Davis Cup Asia/Oceania Zone after Somdev Devvarman and Rohan Bopanna lost their singles rubbers, handing Japan a 2-0 lead on the opening day of the World Group play-off tie in Tokyo on Friday.
Somdev, ranked 65th, suffered an unexpected 3-6 4-6 5-7 defeat against Yuichi Sugita, who is placed 110 rungs below the Indian.
The visitors never recovered from the shock of the opening singles rubber, which lasted two hours and 32 minutes.
India needed an exceptional performance from Bopanna to come back in the tie but the Indian was no match to the supremely talented Kei Nishikori.
World number 55 Nishikori showed his superiority by disbanding Bopanna's challenge 6-3 6-2 6-2 in the second singles, which was over in just one hour and 37 minutes.
India now face the daunting task of winning all the remaining rubbers over the next two days if they have to stay in the elite 16-nation World Group.
Japan, on the other hand, have very strong chance to advance to World Group after a long gap of 26 years.
After the first day debacle, it will be interesting to see which pair Indian captain S P Misra chooses to play in the do-or-die doubles rubber tomorrow as a defeat would end India's chances.
Somdev, who has been India's hero in the Davis Cup for quite some time now, fell to a charged up Sugita, egged on by the home crowd.
There was no margin of error in the first rubber of the tie and whoever blinked had to pay the price. All the three sets were fought closely and it was Somdev who dropped serve early in the first two sets to hand advantage to Sugita.