Question: In which sport did the Czech stars Daniel Vacek and Hana Mandlíková gain professional status?

full_context: Document 1: Pavel Složil: Pavel Složil (born 29 December 1955) is a former professional tennis player from Czechoslovakia.
Document 2: Martina Navratilova: Martina Navratilova (Czech: "Martina Navrátilová" ] ; born Martina Šubertová ] ; October 18, 1956) is a former Czechoslovak and later American tennis player and coach. In 2005, "Tennis" magazine selected her as the greatest female tennis player for the years 1965 through 2005 and she is considered one of the best, if not the best, female tennis players of all time.
Document 3: Martina Hingis: Martina Hingis (born 30 September 1980) is a Swiss professional tennis player, a former world No. 1 singles player and currently ranked world No. 2 in doubles by the WTA. She has spent a total of 209 weeks as the singles No. 1 and has won five Grand Slam singles titles, thirteen Grand Slam women's doubles titles, winning a calendar-year doubles Grand Slam in 1998, and seven Grand Slam mixed doubles titles; for a combined total of twenty-five major titles. In addition, she has won the season-ending WTA Championships two times in singles and three times in doubles, and an Olympic silver medal.
Document 4: 1988 Virginia Slims of Washington – Singles: Hana Mandlíková was the defending champion but lost in the semifinals to Martina Navratilova.
Document 5: Hana Mandlíková: Hana Mandlíková (born 19 February 1962) is a former professional tennis player from Czechoslovakia who later obtained Australian citizenship. During her career, she won four Grand Slam singles titles: the 1980 Australian Open, 1981 French Open, 1985 US Open, and the 1987 Australian Open. She was also the runner-up at four Grand Slam singles events, including the Wimbledon finals of 1981 and 1986, and won one Grand Slam women's doubles title, the 1989 US Open with Martina Navratilova.
Document 6: Tomáš Šmíd: Tomáš Šmíd (born May 20, 1956 in Plzeň) is a former tennis player from Czechoslovakia, who won nine singles titles during his career. In doubles, he won fifty-four titles and was World No. 1 in doubles from December 17, 1984 to August 11, 1985. The right-hander reached his highest ATP singles ranking of World No. 11 in July 1984. Šmíd participated in 31 Davis Cup ties for Czechoslovakia from 1977–1989, posting a 20-10 record in doubles and a 22-15 record in singles.
Document 7: Radek Štěpánek: Radek Štěpánek (] ; born 27 November 1978) is a professional tennis player from the Czech Republic. His career-high singles ranking is world No. 8 and best doubles ranking is world No. 4. Štěpánek's biggest achievements are reaching two Masters 1000 event finals and the quarterfinals of Wimbledon in 2006, as well as winning the deciding match for Czech Republic's Davis Cup winning team in 2012 and again in 2013. In doubles, he won his first Grand Slam title at the 2012 Australian Open, along with Indian partner Leander Paes, defeating the Bryan Brothers in the final. Paes and Štěpánek also won the men's doubles title at the 2013 US Open, defeating Bruno Soares and Alexander Peya in the final.
Document 8: Cyril Suk: Cyril Suk III (born 29 January 1967) is a former professional tennis player. A doubles specialist, Suk won one Grand Slam men's doubles title and four Grand Slam mixed doubles titles during his career.
Document 9: Daniel Vacek: Daniel Vacek (born 1 April 1971) is a former tennis player from Czechoslovakia and the Czech Republic who turned professional in 1990. He reached the quarterfinals of the 1995 Paris Masters, the 1998 Canada Masters and the 1998 Cincinnati Masters, and achieved a career-high singles ranking of World No. 26 in January 1996.
Document 10: Evert–Mandlikova rivalry: The tennis players Chris Evert (United States) and Hana Mandlíková (Czechoslovakia/Australia) met 26 times during their careers. Evert leads their overall head-to-head series 19–7. In 1981 the rivalry was described as being the most "dramatic" in women's tennis.
Document 11: 1984 US Open – Women's Singles: Martina Navratilova was the defending champion, and she successfully defended her title, defeating last year's finalist Chris Evert in the final. This victory was Navratilova's sixth straight Major title, tying her with Margaret Court and Maureen Connolly for the most consecutive Grand Slam titles won. Navratilova became the first player to win Grand Slams on clay, grass and hard court on the same calendar year, after having won the French Open and Wimbledon.
Document 12: Daniel Nestor: Daniel Mark Nestor {'1': ", '2': ", '3': ", '4': "} (Serbian Cyrillic: Данијел Несторовић; born September 4, 1972 as Danijel Nestorović) is a Canadian professional tennis player. He is one of the foremost doubles players in tennis history due to his longevity and continued success at the top of the men's game. s of 2016 , he is 11th for most men's ATP titles in Open Era history. In January 2016, Nestor became the first doubles player in ATP history to win 1000 matches.
Document 13: 1988 Australian Open – Women's Singles: Hana Mandlíková was the defending champion, but was defeated by Steffi Graf in the quarterfinals. Graf ended up winning the tournament, defeating Chris Evert in the final, 6–1, 7–6. This would be Chris Evert's 34 appearance in a Grand Slam final, an Open Era record, and her 6th final, Evert made the final in every Australian Open she played. This was the first Grand Slam Final played under a roof. There was an 1 hour and 23 minute delay to close the roof at 1-1 in the first set. This was Graf's first step towards completing the first and so far only calendar year Golden Slam.
Document 14: Vasek Pospisil: Vasek Pospisil (, ] ; born June 23, 1990) is a Canadian professional tennis player. He is the No. 3 male ranked player in Canada, after Milos Raonic and Denis Shapovalov. Pospisil has a career-high World singles ranking of 25, and No. 4 in doubles. As Canada's currently ranked No. 3 in singles and No. 3 in doubles, he is an important member of the Canada Davis Cup team. Along with partner Jack Sock, he won the 2014 Wimbledon Championships and the 2015 Indian Wells Masters men's doubles titles. He also reached the quarterfinals in singles at the 2015 Wimbledon Championships.
Document 15: Pavel Vojtisek: Paul Vojtischek (born Pavel Vojtíšek, 13 June 1963) is a Czechoslovak-born West German retired professional tennis player. Vojtisek, who got West German citizenship in his early 20s, is married to two-time Grand Slam finalist Renáta Tomanová.
ground_truth: tennis