Krishnan was an outstanding tennis player in his youth. In 1979, he won the junior tournaments in the French Open and Wimbledon and the semi-finals of the junior competition of the U.S. Open. Between 1981 and 1990, Krishnan won eight singles titles and one doubles title on the ATP World Tour. In addition, two single title came on the ATP Challenger Tour. However, Krishnan, whose father Ramanathan is one of the Indian tennis legends deserved, especially as Davis Cup player praise and recognition. In 1977, he celebrated with a victory against Moon - Il Kim (South Korea) made his debut as Davis Cup player and was the team fifteen years to 1993. He led the Indian Davis Cup team in the 1987 season with a record of 7-1 in singles finals; the final in Gothenburg, however, was lost 0:5. In his final season as a player he defeated in Frejus Rodolphe Gilbert with 2:6, 6:4, 4:6, 7:5, 6:4.
In 2000, took over Ramesh Krishnan, who took over his father's tennis school in Madras, the Indian Davis Cup captain Office of Jaidip Mukerjea. Henceforth, India qualified every year for the duels for the promotion to the World Group, but never could prevail there permanently. After the expected 0-5 defeat in September 2003 in Zwolle against the Netherlands Krishnan announced his retirement, and was succeeded by the still active Indian tennis player Leander Paes.