Question: Which tennis player, Andrei Olhovskiy or Hana Mandlíková, won four Grand Slam singles titles?

Context paragraphs:
Li Na: Li Na (; ; born 26 February 1982) is a retired Chinese professional tennis player, who achieved a career-high WTA-ranking of world No. 2 on 17 February 2014.  Over the course of her career, Li won seven WTA singles titles and two Grand Slam singles titles at the 2011 French Open and 2014 Australian Open.  Li's rise to prominence came after those victories, which made her the first and only Grand Slam singles champion from East Asia and Asia as a whole.  Prior to this, she had already become the first player representing an East Asian and Asian country to appear in a Grand Slam singles final, a milestone she achieved at the 2011 Australian Open.  Li was also the runner-up at the 2013 Australian Open and 2013 WTA Tour Championships, a three-time quarterfinalist at Wimbledon and a semifinalist at the 2008 Beijing Olympic Games and 2013 US Open.  Among her other most notable accolades, she was the first Chinese player to win a WTA tour title at the Guangzhou International Women's Open in 2004, the first to reach a Grand Slam singles quarterfinal at the 2006 Wimbledon Championships, and the first to break into the world's top 10.  Her feats have sparked a major population growth of tennis players in East Asia, earning her the reputation as the region's tennis pioneer and trailblazer.

Sandra Reynolds: Sandra Reynolds Price ("née" Reynolds; born 4 March 1934) is a former tennis player from South Africa who won four Grand Slam women's doubles championships and one Grand Slam mixed doubles championship.  Her best Grand Slam singles result was reaching the 1960 Wimbledon final, losing to Maria Bueno 8–6, 6–0.  Reynolds is the only female player from South Africa to have reached the Wimbledon singles final, and she is one of three to have reached a singles final in a Grand Slam.  In 1961, she was seeded no. 1 for the Wimbledon Ladies Singles Championship, making her the only South African player (man or woman) ever to be seeded first in a Grand Slam singles event.  She was the runner-up at the 1959 , losing to Sally Moore in the final.  Price won the German Championships in 1960, 1961, and 1962.  She was the runner-up at the 1959 Italian Championships, having defeated Bueno in a semifinal, then losing to Christine Truman in the final.

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.

Jim Courier: James Spencer Courier Jr. (born August 17, 1970) is an American former World No. 1 professional tennis player.  During his career, he won four Grand Slam singles titles, two at the French Open and two at the Australian Open.  He holds the record for being the youngest man to have reached the finals of all four Grand Slam singles tournaments, at the age of 22 years and 11 months.  He also won five Masters 1000 series titles.  Until Novak Djokovic in 2016, Courier was the last man to win both the Australian and French Opens in the same calendar year.

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.

Andrei Olhovskiy: Andrei Stanislavovich Olhovskiy (Russian: Андрей Станиславович Ольховский ) (born 15 April 1966) is a former tennis player from Russia, who turned professional in 1989.

Arantxa Sánchez Vicario: Aránzazu Isabel María "Arantxa" Sánchez Vicario (] ; born 18 December 1971) is a Spanish former World No. 1 professional tennis player.  She won four Grand Slam singles titles, six Grand Slam women's doubles titles, and four Grand Slam mixed doubles titles.  In 1994 she was crowned the ITF World Champion for the year.

Williams sisters: The Williams sisters are two professional American tennis players: Venus Williams (b. 1980), a seven-time Grand Slam title winner (singles), and Serena Williams (b. 1981), twenty-three-time Grand Slam title winner (singles), both of whom were coached from an early age by their parents Richard Williams and Oracene Price.  There is a noted professional rivalry between them – between the 2001 US Open and the 2017 Australian Open tournaments, they met in nine Grand Slam singles finals.  They became the first two players, female or male, to play in 4 consecutive grand slam singles finals from the 2002 French Open to the 2003 Australian Open; Serena famously won all 4 to complete the first of two "Serena Slams".  Between 2000 and 2016, a 17-year span, they collectively won 12 Wimbledon singles titles (Venus won 5 and Serena won 7).  By winning the 2001 Australian Open women's doubles title, they became the 5th pair to complete the Career Doubles Grand Slam and the only pair to complete the Career Doubles Golden Slam.  At the time, Venus and Serena were only 20 and 19 years old, respectively.  Since then they have gone on to add another two Olympic gold medals in the 2008 Beijing Olympics and the 2012 London Olympics.  Nearly a decade later, the duo would go on to win 4 consecutive grand slam doubles titles from 2009 Wimbledon through 2010 Roland Garros, which would catapult them to co-No.  1 doubles players on 7 June 2010.  Two weeks later, on 21 June 2010, Serena would hold the No. 1 singles ranking and Venus would be right behind her at No. 2 in singles.  Their most recent grand slam doubles titles came at the 2012 Wimbledon & 2016 Wimbledon events.  They remain very close, often watching each other's matches in support, even after one of them has been knocked out of a tournament.

Steffi Graf: Stefanie Maria "Steffi" Graf (] ; born 14 June 1969) is a German former tennis player, who was ranked world No. 1 during her career.  Graf won 22 Grand Slam singles titles.  Her 22 singles titles put her second on the list of Major wins in the female competition since the introduction of the Open Era in 1968 and is third all-time behind Margaret Court (24) and Serena Williams (23).  In 1988, she became the first and only tennis player (male or female) to achieve the Golden Slam by winning all four Grand Slam singles titles and the Olympic gold medal in the same calendar year.  Furthermore, she is the only tennis player to have won each Grand Slam event at least four times.

Yevgeny Kafelnikov: Yevgeny Aleksandrovich Kafelnikov (Russian: Евгений Александрович Кафельников ] ; born 18 February 1974) is a Russian former world No. 1 tennis player.  He won two Grand Slam singles titles, the 1996 French Open and the 1999 Australian Open.  He also won four Grand Slam doubles titles, being the last man to have won both the men's singles and doubles titles at the same Grand Slam tournament, which he did at the 1996 French Open.

Supporting paragraphs: Andrei Olhovskiy Hana Mandlíková
Answer: Hana Mandlíková