Question:  Liezel Huber and Arantxa Sánchez Vicario, are both six time Grand Slam title winners of what sport?

Context articles: Karina Habšudová
1994 Australian Open – Mixed Doubles
1994 US Open – Women's Singles
1995 Wimbledon Championships – Women's Singles
Arantxa Sánchez Vicario
Liezel Huber
1996 US Open – Women's Doubles
1997 Bausch &amp; Lomb Championships – Doubles
1989 French Open – Women's Singles
1996 Wimbledon Championships – Women's Singles

Karina Habšudová (born 2 August 1973) is a Slovak former professional tennis player.
 She has been ranked as high as 10 in the world (1997).
 Together with Karol Kučera she won the Hopman Cup in 1998.
 Her best performance at a Grand Slam came when she got to the quarter finals of the 1996 French Open, defeating Kristin Godridge, Nathalie Tauziat, Martina Hingis and Anke Huber before losing to Arantxa Sánchez Vicario.
Arantxa Sánchez Vicario and Todd Woodbridge were the defending champions but they competed with different partners that year, Sánchez Vicario with Emilio Sánchez and Woodbridge with Helena Suková.
Steffi Graf was the defending champion, but she was defeated in the final by Arantxa Sánchez Vicario, marking the last time Sánchez Vicario defeated Graf at any tournament.
Conchita Martínez was the defending champion, but she lost to Arantxa Sánchez Vicario in the semifinals.
 Steffi Graf defeated Sánchez Vicario 4–6, 6–1, 7–5 in the final to win the Ladies' Singles tennis title at the 1995 Wimbledon Championships, giving Graf the sixth Wimbledon title of her career.
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.
Liezel Huber (née Horn; born 21 August 1976) is a South African-American retired tennis player who represents the United States internationally.
 Huber has won four Grand Slam titles in women's doubles with partner Cara Black, one with Lisa Raymond, and two mixed doubles titles with Bob Bryan.
 On 12 November 2007, she became the co-World No. 1 in doubles with Cara Black.
 On 19 April 2010, Huber became the sole No. 1 for the first time in her career.
Gigi Fernández and Natasha Zvereva were the defending champions and successfully defended their title, defeating Jana Novotná and Arantxa Sánchez Vicario 1–6, 6–1, 6–4 in the final.
 It was the 5th US Open, 15th Grand Slam and 66th overall title for Fernández, and the 4th US Open, 15th Grand Slam and 60th overall title, in their respective careers.
Chanda Rubin and Arantxa Sánchez Vicario were the defending champions but they competed with different partners that year, Rubin with Brenda Schultz-McCarthy and Sánchez Vicario with Larisa Savchenko.
Steffi Graf was the two-time defending champion, but lost in the final to 17-year-old Arantxa Sánchez Vicario, 7–6, 3–6, 7–5, ending her winning streak of Grand Slam singles titles at five.
 Graf served for the championship at 5–3 in the third set, but lost the game at love and won only three more points in the match from that point.
 It was the first of Sánchez Vicario's three French Open titles, which she also won in 1994 and 1998.
Steffi Graf was the defending champion, and she successfully defended her title, defeating Arantxa Sánchez Vicario in the final, in what was a rematch of last year's final.
 With the victory, Graf captured her seventh and final Wimbledon crown, while it marked Sánchez Vicario's last appearance in the ladies' championship match.