Question: Which tennis player, Daniel Vacek or Andre Agassi, achieved a career-high singles ranking of World No. 26 in January 1996?
Context: Johan Kriek (born April 5, 1958) is a South African-American professional male tennis player and founder of the Global Water Foundation, a non-profit organization dedicated to delivering clean water to the world's neediest communities.  Kriek won two Australian Opens and reached the semifinals at the French Open and US Open, as well as the quarterfinals of Wimbledon.  He won 14 professional singles and 8 doubles titles, reaching a career-high singles ranking of World No. 7.  Kriek's most memorable wins include victories over Andre Agassi, Jimmy Connors, John McEnroe, Guillermo Vilas, Stefan Edberg, Michael Chang, Vitas Gerulaitis and Björn Borg. Andre Kirk Agassi ( ; born April 29, 1970) is an American retired professional tennis player and former World No. 1 who was one of the sport's most dominant players from the early 1990s to the mid-2000s.  Generally considered by critics and fellow players to be one of the greatest tennis players of all time, Agassi has been called the greatest service returner in the history of the game.  Described by the BBC upon his retirement as "perhaps the biggest worldwide star in the sport's history", Agassi compiled performances that, along with his unorthodox apparel and attitude, saw him cited as one of the most charismatic players in history.  As a result, he is credited for helping to revive the popularity of tennis during the 1990s. Stefan Simonsson (born 5 January 1960, in Hyltebruk), is a former professional tennis player from Sweden.  He enjoyed most of his tennis success while playing singles.  During his career he won 2 doubles titles.  He achieved a career-high singles ranking of World No. 49 in 1983 and a career-high doubles ranking of World No. 88 in 1984.  He´s the brother of Hans Simonsson.  After his career, he coached two top 10 players on the ATP ranking, Magnus Gustavsson and Magnus Larsson. 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. Glenn Layendecker (born May 9, 1961) is a former professional tennis player from the United States.  His highest singles ranking was World No. 48 in 1990.  His highest doubles ranking was World No. 32.  Layendecker's career wins included Andre Agassi, Michael Chang, Yannick Noah, Aaron Krickstein, Anders Järryd, and Brad Gilbert in singles matches.  He also beaned John McEnroe in the temple with an approach shot at the US Open. Fernando Verdasco Carmona (] ; (born 15 November 1983) is a Spanish professional tennis player.  His career-high singles ranking is world No. 7, achieved in April 2009.  Verdasco started playing tennis at four years of age and had a full-time coach when he was eight.  As of 2009, Verdasco has been working in Las Vegas with Andre Agassi and his team, including Darren Cahill (Agassi's former coach) and Gil Reyes (Agassi's fitness coach). Jérôme Haehnel (born 14 July 1980) is a retired French tennis player who is best known for defeating Andre Agassi in the first round of the French Open in 2004.  Haehnel's career-high singles ranking is World No. 78, which he reached in February 2005.  Jerome was coached by his wife and has a fear of flying. Hicham Arazi (Arabic: هشام أرازي‎ ‎ ; born 19 October 1973) is a former male tennis player from Morocco.  He played professionally from 1993 to the end of 2007.  The left-hander reached his career-high ATP Tour singles ranking of world No. 22 on November 5, 2001.  During his career, Arazi captured one singles title, in Casablanca.  "The Moroccan Magician" reached the quarter-finals of the Australian Open twice and the French Open twice.  As well as the aforementioned nickname, some tennis analysts called him "The Moroccan McEnroe" due to his talent - he played with incredible touch, and often enjoyed the support of the crowd even when not at home.  He led Patrick Rafter, winner of the US Open in 1997 and 1998, two sets to love during the first round of the latter tournament.  In the third set he was upset with several line calls, telling umpire Norm Chryst to "get out of here", which sparked the beginning of Arazi's meltdown (and Rafter's comeback).  During his career, he notably gained victories over former World No. 1s and Grand Slam champions Roger Federer, Andre Agassi, Yevgeny Kafelnikov, Marat Safin, Lleyton Hewitt, Juan Carlos Ferrero, Carlos Moyá and Jim Courier. 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. Andre Begemann (born July 12, 1984) is a German professional tennis player.  He is a doubles specialist who reached his career-high doubles ranking of world No. 36, achieved in May 2015.  He has a career-high singles ranking of No. 166, achieved in July 2010.
Answer: Daniel Vacek