Kei Nishikori eased to a comfortable straight sets win against Rohan Bopanna on Friday to help Japan to a 2-0 lead over India in their Davis Cup World Group playoff tie.
In the opening match on the Ariake Coliseum hard court, Japan's world number 175 Yuichi Sugita caused an upset with a 6-3, 6-4, 7-5 win over 65th-ranked Somdev Devvarman.
Nishikori, ranked 55th against Bopanna's 559th, scored an early break in each set to chalk up a 6-3, 6-2, 6-2 victory to put Japan two up.
Japan, who have only three wins and 18 defeats against India previously, have not made it to the Davis Cup's World Group top tier since 1985. They advanced to the play-off by beating Uzbekistan 4-1 in July.
India were beaten in the World Group first round for the second consecutive year, losing to Serbia 4-1.