On his Test match debut, Viswanath scored a century against
Australia at
Kanpur in 1969 in a drawn match. He also recorded a duck in the same game, one of only four batsmen to have done this in their first match. Viswanath is the first and only player to score a
double century on first-class debut as well as a century on Test debut. His best performances tended to come on challenging pitches, and while some of his best innings did not result in centuries, they were still important to the team's success. Against
Australia and the
West Indies, both known for their strong pace attacks, he had a batting average of over 50. He was at his peak in the mid-1970s. Against the West Indies at
Madras in 1974–75 he scored 97 not out out of a total of 190 against a bowling attack containing
Andy Roberts. Despite not being a century, it was regarded as one of the finest performances by an Indian and it led to an Indian victory. The
Wisden 100 ranked it the 38th best innings of all time, and the second best non-century. He scored a match-winning century in the previous Test at
Calcutta, but despite a 95 in the final Test at
Bombay the series was lost 3–2. In 1975–76, Viswanath again produced some strong performances against the West Indies, the most notable of which was his 112 at
Port of Spain which helped India to reach the victory target of 403. At the time, this was the highest successful run-chase in Test cricket. In 1978–79 at Madras he again top scored with 124 out of a total of 255. India went on to win the match which ultimately led to a 1–0 series victory in the 6-match series, although this West Indian side was considerably weaker than in previous series after many players opted to play in
World Series Cricket instead. ==Captaincy==