Aged 17, Hantze reached the Quarter Finals of the women's singles at the
United States Championships in 1959. She made her debut at
Wimbledon in the summer of 1960, reaching the Quarter Finals of the women's singles, but going on to win the Junior Girls' singles championship. After reaching the singles Quarter Finals again in 1961, Hantze and
Billie Jean Moffitt, as an unseeded team, won the 1961 women's doubles title at Wimbledon, defeating the third-seeded team of
Jan Lehane and
Margaret Smith in the final in straight sets. Their combined ages made them the youngest team to win the title at the time. Returning as Mrs. Susman in 1962 and seeded eighth in the singles, Susman won the women's singles in 1962 without losing a set. She became the first player in Wimbledon history to win both the junior and adult singles' events. Susman and Moffitt successfully defended their doubles title in 1962, defeating the South African team of
Renée Schuurman and
Sandra Reynolds in a three-set final. Due to her pregnancy, Susman did not play at Wimbledon in 1963, but she returned in 1964 and unseeded, lost in the last 32 to the top seeded Margaret Smith, 11-9 6–0. Susman and Moffitt reached the 1964 women's doubles final at Wimbledon, losing to the top-seeded team of Smith and
Lesley Turner. For Wimbledon's centenary celebration in 1977, Susman and (Moffitt) King teamed for the last time. As the eighth-seeded team, they were upset in the second round by the team of
Mary Carillo and
Trish Bostrom. Susman and Moffitt won the 1964 women's doubles title at the
U.S. Championships, defeating Smith and Turner in the final in three sets. Susman and Moffitt reached the 1962 women's doubles final at the U.S. Championships, losing to the team of
Maria Bueno and
Darlene Hard in three sets. They also reached the 1965 women's doubles final at the U.S. Championships, losing to the team of
Nancy Richey and
Carole Caldwell Graebner. Susman gave birth to her only child in October 1963 and played very little in 1963, deciding not to defend her Wimbledon singles and doubles titles. She returned to play in 1964, and at Wimbledon, she lost in a third-round match to
Margaret Smith. She entered the U.S. Championships the same year, but withdrew before the tournament. Susman played little in the 1960s and 1970s, but joined the start of Team Tennis in the U.S. in 1974 and made occasional tournament appearances, Susman was included in the year-end top 10 rankings issued by the
United States Lawn Tennis Association from 1959 through 1962 and in 1964. She was the second-ranked U.S. player behind Hard from 1960 through 1962. ==Grand Slam finals==