Question: who is younger Joakim Nyström or Kimberly Po ?

full_context: Document 1: Kimberly Po: Kimberly Po-Messerli (born October 20, 1971) is a former professional tennis player from the United States.
Document 2: Mats Wilander: Mats Wilander (] ; born 22 August 1964) is a former World No. 1 tennis player from Sweden. From 1982 to 1988, he won seven Grand Slam singles titles (three at the French Open, three at the Australian Open, and one at the US Open), and one Grand Slam men's doubles title (at Wimbledon).
Document 3: Tom Okker: Thomas Samuel Okker (born 22 February 1944) is a former Dutch tennis player. He was ranked among the world's top 10 singles players for seven consecutive years, 1968–74, reaching a career high of World No. 3 in 1969. He also was ranked World No. 1 in doubles in 1969.
Document 4: Stefan Edberg: Stefan Bengt Edberg (] ; born 19 January 1966) is a Swedish former world no. 1 professional tennis player (in both singles and doubles). A major proponent of the serve-and-volley style of tennis, he won six Grand Slam singles titles and three Grand Slam men's doubles titles between 1985 and 1996. He also won the Masters Grand Prix and was a part of the Swedish Davis Cup-winning-team four times. In addition he won four Masters Series titles, four Championship Series titles and the unofficial Olympic tournament 1984, was ranked in the singles top 10 for ten successive years, 9 years in the top 5, and is considered one of the greatest players of his era. Edberg began coaching Roger Federer in January 2014, with this partnership ending in December 2015.
Document 5: Jennifer Capriati: Jennifer Maria Capriati (born March 29, 1976) is an American former professional tennis player. A member of the International Tennis Hall of Fame, she won three singles championships in Grand Slam tournaments and a gold medal at the 1992 Summer Olympics in Barcelona, reached the World No. 1 ranking, and is considered one of the greatest tennis players of all time.
Document 6: Mary Joe Fernández: Mary Joe Fernández Godsick (born María José Fernández; August 19, 1971) is an American former professional tennis player. She reached a career-high ranking of world No. 4 in both singles and doubles. Fernández was the runner-up in three Grand Slam singles tournaments and won two Grand Slam women's doubles titles and two Olympic gold medals.
Document 7: 1986 ABN World Tennis Tournament: The 1986 ABN World Tennis Tournament was a men's tennis tournament played on indoor carpet courts at Ahoy Rotterdam in the Netherlands that was part of the 1986 Nabisco Grand Prix. It was the 14th edition of the tournament and was held from 24 March through 30 March 1986. Fourth-seeded Joakim Nyström won the singles title.
Document 8: Zina Garrison: Zina Lynna Garrison (born November 16, 1963) is a former professional tennis player from the United States. During her career, she was a women's singles runner-up at Wimbledon in 1990, a three-time Grand Slam mixed doubles champion, and a women's doubles gold medalist and singles bronze medalist at the 1988 Olympic Games. She is currently coaching Taylor Townsend.
Document 9: Tracy Austin: Tracy Ann Austin Holt (born December 12, 1962) is an American former World No. 1 retired professional tennis player. She won three Grand Slam titles, including the women's singles titles at the 1979 and 1981 US Opens, and the mixed doubles title at the Wimbledon Championships in 1980. Additionally, she won the WTA Tour Championships in 1980 and the year-ending Toyota Championships in 1981, both in singles. A series of injuries and a serious automobile accident cut short her career. Since 1979, she has been the youngest US Open female singles champion in history, and she is the youngest inductee of all time at the International Tennis Hall of Fame. Austin won singles titles on all playing surfaces: clay (both red clay and green clay), indoor carpet, grass, and hard courts.
Document 10: Balázs Taróczy: Balázs Taróczy (Hungarian: "Taróczy Balázs" ; born 9 May 1954) is a retired tennis player from Hungary, who won thirteen singles titles in his career. The right-hander achieved his career-high ATP singles ranking of World No. 12 in April 1982.
Document 11: Kim Clijsters: Kim Antonie Lode Clijsters (] ; born 8 June 1983) is a Belgian former professional tennis player. Clijsters is a former world No. 1 in both singles and doubles.
Document 12: Joakim Nyström: Joakim "Jocke" Nyström (born 20 February 1963) is a former top ten ranked tennis player from Sweden who won 13 singles titles during his professional career. The right-hander reached his highest singles ranking on the ATP Tour on 31 March 1986, when he was ranked World No. 7 and was also ranked as high as World No. 4 in doubles that same year.
Document 13: Boris Becker: Boris Franz Becker (] ; born 22 November 1967) is a German former world No. 1 professional tennis player. He was successful from the start of his career, winning the first of his six major singles titles aged 17. He also won five year-end championships, 13 Masters Series titles, and an Olympic gold medal in doubles. "Tennis" magazine ranked him the 11th best male player of the period 1965–2005.
Document 14: Pam Teeguarden: Pam Teeguarden (born April 17, 1951) is a former American professional tennis player in the 1970s and 1980s, ranked in the top 20 from 1970–1975, according to "John Dolan's Women's Tennis Ultimate Guide", prior to computer rankings. She won two Grand Slam Doubles Titles and was a quarter finalist in singles at the U.S. Open and The French Open. Her father Jerry, a well known coach, helped Margaret Court win the coveted Grand Slam (all four Grand Slam titles in one year) in 1970 and Virginia Wade to her 1977 Wimbledon triumph. Teeguarden was voted the "Most Watchable Player" based on play and appearance by a group of Madison Avenue advertising executives or "Mad Men" while playing at the US Open. Teeguarden played in 19 consecutive US Opens, holding the record until Chris Evert played in 20. She wore the first all black outfit in the history of tennis in 1975 at The Bridgestone Doubles Championships in Tokyo, starting a trend that is still popular today. Teeguarden was the first woman tennis player signed by Nike. She played on the victorious Los Angeles Strings Team Tennis team in 1981 and won the Team Tennis Mixed Doubles Division with Tom Gullikson in 1977; they were also runners-up in the league that year.
Document 15: 1990 SkyDome World Tennis Tournament – Singles: Joakim Nyström was the champion of the event when it last took place, in 1986. He did not participate in 1990.<br>Ivan Lendl won the title, defeating Tim Mayotte 6–3, 6–0, in the final.
ground_truth: Kimberly Po-Messerli