Were Mariaan de Swardt and Ken Rosewall both professional tennis players?
Ken Rosewall Kenneth Robert Rosewall {'1': ", '2': ", '3': 'AM, MBE', '4': "} (born 2 November 1934) is a former world top-ranking amateur and professional tennis player from Australia. He won a record 23 tennis Majors including 8 Grand Slam singles titles and before the Open Era a record 15 Pro Slam titles and a record 35 Major finals overall. He won the Pro Grand Slam in 1963. Rosewall won 9 slams in doubles with a career double grand slam. He is considered to be one of the greatest tennis players of all time. He had a renowned backhand and enjoyed a long career at the highest levels from the early 1950s to the early 1970s. Rosewall was one of the two best male players for about nine years and was the World No. 1 player for a number of years in the early 1960s. He was ranked among the top 20 players, amateur or professional, every year from 1952 through 1977. Rosewall is the only player to have simultaneously held Pro Grand Slam titles on three different surfaces (1962–1963). At the 1971 Australian Open he became the first male player during the open era to win a Grand Slam tournament without dropping a set.
Kenneth Carlsen Kenneth Carlsen (born 17 April 1973) is a Danish former professional tennis player, who was active between 1992 and 2007. Carlsen played left-handed with a one-handed backhand. His greatest asset was his powerful serve, and his game was therefore best suited to fast surfaces (grass and hardcourt) . For most of his long career Carlsen was Denmark's best tennis player, and consistently among the few Danish players playing at the highest international level. He was awarded as best Danish "Tennis Player of the Year" seven times by the Danish Tennis Federation (first time in 1991, last time in 2005). Two times the award went to the Danish Davis Cup team, of which Kenneth Carlsen until 2003 was a central part (having a 29–13 record in singles).