Question: Which tennis player reached a higher World singles ranking, Allan Stone or Kevin Curren?
Context: 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. Kevin Melvyn Curren (born 2 March 1958) is a South African-American former professional tennis player.  He played in two Grand Slam singles finals and won four Grand Slam doubles titles, reaching a career-high singles ranking of World No. 5. John McEnroe was the defending champion but lost in the quarterfinals to Kevin Curren.  Curren also defeated Jimmy Connors in the semifinal and became the first player ever to defeat both Connors and McEnroe in the same Grand Slam tournament. Jim Thomas (born September 24, 1974) is an American former professional tennis player.  His highest ATP world singles ranking was number 288, which he reached on November 2, 1998.  His career high in doubles was at 29, set on August 21, 2006.  He retired following the 2008 season. Ernests Gulbis (] , born 30 August 1988, and nicknamed "The Gull" or "Ernie") is a Latvian professional tennis player.  In 2008, Gulbis won his first ATP Tour doubles title at the U.S. Men's Clay Court Championships, teaming with Rainer Schüttler, and in 2010 won his first ATP Tour singles title in the Delray Beach, defeating Ivo Karlović in the final.  In total, Gulbis has 6 ATP titles to his name and has never lost a final.  His best performance at a Grand Slam is reaching the semifinals of the 2014 French Open.  He had previously reached the quarterfinals of the 2008 French Open.  Gulbis' career-high singles ranking is world No. 10, making him the only Latvian tennis player ever to be ranked inside the top 10 in ATP Singles Ranking.  He achieved this in June 2014. Allan Stone (born 14 October 1945) played amateur and professional tennis in the 1960s and 1970s.  He was ranked as high as World No. 38 in singles on the ATP Rankings in April 1975. Marcel Granollers Pujol (] , ] ; born 12 April 1986) is a tennis player from Spain who turned professional in 2003.  He reached his career-high singles ranking of World No. 19 in July 2012, and his highest doubles ranking of World No. 4 in February 2013.  Granollers has won 4 singles titles and 13 doubles titles, including the 2012 ATP World Tour Finals.  His brother Gerard Granollers is also a tennis player. Dimitar Kuzmanov (Bulgarian: Димитър Кузманов , ] ; nickname: Miko; born 28 July 1993) is a Bulgarian professional tennis player and the current No. 3 Bulgarian in the ATP singles ranking.  His highest singles ranking was No. 281 (8 February 2016), whilst his best doubles ranking was No. 445 (8 February 2016).  Kuzmanov is a player of Tennis Club Lokomotiv Plovdiv and is coached by former Bulgarian tennis player Stefan Rangelov and by Bulgaria Fed Cup team's former tennis player and present captain Dora Rangelova.  In 2011 he was invited to play for Bulgaria Davis Cup team. Roscoe Tanner (born October 15, 1951) is a retired American professional tennis player, who turned pro in 1972 and reached a career-high world singles ranking of World No. 4 on July 30, 1979. Jorge Lozano (born 17 May 1963 in San Luis Potosí) is a retired professional tennis player from Mexico.  He reached his highest doubles ranking of World No. 4 in August 1988.  His highest singles ranking was World No. 51, achieved the following month.  During his career, he won two mixed doubles titles at the French Open: in 1990 with Arantxa Sánchez, and in 1988 with Lori McNeil.  He reached the round of 16 in singles at the 1988 US Open and also the semifinal in doubles that same year.  Qualified twice for the Doubles Masters at the Royal Albert Hall in London and reached the semifinals in 1988.  In his career, he won nine doubles titles, but no singles titles.  He turned professional in 1986, and in his career, he won $U.S.739,424 in prize money.  He was the first player to be beaten by Pete Sampras in the main draw of a Grand Slam tournament, at the French Open in 1989.  In Davis Cup play, represented Mexico for 15 years, 1981–1995, won 12 doubles matches, and lost 12 as well.  He lost 11 singles matches, and won 8, making his overall win / loss record at the Davis Cup 20–23.  Lozano won his first title at Forest Hills in 1988, with his partner Todd Witsken, and won his last at Athens in 1993.  He resides in Guadalajara, Mexico where he directs a tennis academy for kids and also coaches the men and women tennis team at the University Tec de Monterrey.  He is currently the captain of the Mexican Davis Cup Team.
Answer: Kevin Melvyn Curren