Question: Who won more championship titles (either Grand Slam or Masters 1000), Thomas Muster or Betty Stöve?

<P0-S0> 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. <P0-S1>  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. <P0-S2>  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". <P0-S3>  Between 2000 and 2016, a 17-year span, they collectively won 12 Wimbledon singles titles (Venus won 5 and Serena won 7). <P0-S4>  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. <P0-S5>  At the time, Venus and Serena were only 20 and 19 years old, respectively. <P0-S6>  Since then they have gone on to add another two Olympic gold medals in the 2008 Beijing Olympics and the 2012 London Olympics. <P0-S7>  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. <P0-S8>  1 doubles players on 7 June 2010. <P0-S9>  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. <P0-S10>  Their most recent grand slam doubles titles came at the 2012 Wimbledon & 2016 Wimbledon events. <P0-S11>  They remain very close, often watching each other's matches in support, even after one of them has been knocked out of a tournament. <SEP> <P1-S0> Thomas Muster (born 2 October 1967) is a former World No. 1 tennis player from Austria. <P1-S1>  One of the world's leading clay court players in the 1990s, he won the 1995 French Open and at his peak was known as "The King of Clay." <P1-S2>  In addition, he won eight Masters 1000 series titles. <P1-S3>  Muster is one of only three players to win Masters titles on the three different surfaces of clay, carpet, and hard court. <SEP> <P2-S0> Frederick V. McNair IV (born July 22, 1950 in Washington, D.C.) is a former professional tennis player from the United States who reached the World No. 1 doubles ranking in 1976. <P2-S1>  That year, he teamed up with Sherwood Stewart to capture the men's doubles titles at French Open, the German Open and the Masters. <P2-S2>  McNair was also a mixed doubles runner-up at the French Open in 1981, partnering Betty Stöve. <P2-S3>  In 1978, he was a member of the US team that won the Davis Cup. <P2-S4>  In nine years on the professional tour, McNair won 16 doubles titles. <P2-S5>  His career-high singles ranking was World No. 67. <SEP> <P3-S0> Betty Stöve (born 24 June 1945) is a Dutch former professional tennis player. <P3-S1>  She is best remembered for reaching the ladies' singles final at Wimbledon in 1977. <P3-S2>  She also won ten Grand Slam titles in women's doubles and mixed doubles.