Lendl turned professional in 1978. After reaching his first top-level singles final in 1979, he won seven singles titles in 1980, including three tournament wins in three consecutive weeks on three different surfaces. Lendl was part of Czechoslovakia's Davis Cup winning team that year. He was the driving force behind the country's team in the first half of the 1980s, and was also part of the Czechoslovak team that won the World Team Cup in 1981 and was runner-up in 1984 and 1985. However, he stopped playing in these events after he moved to the United States in 1986 because Czechoslovakia's Tennis Association viewed him as an "illegal defector" from their country.