quality:correction, stylistic:tone
Early life and background

Suzanne Rachel Flore Lenglen was born in the 16th arrondissement of Paris on 24 May 1899 to Charles and Anaïs Lenglen (née Dhainault). She had a younger brother who did not live past the age of three. Lenglen's father was a pharmacist who became wealthy by inheriting a horse-drawn omnibus company from his father. Several years after Suzanne was born, her father sold the omnibus business, after which he relocated the family to Marest-sur-Matz near Compiègne in northern France in 1904. They spent their winters in Nice on the French Riviera in a villa across the street from the Nice Lawn Tennis Club. By the time Lenglen was eight, she excelled at a variety of sports, including swimming and cycling. In particular, she enjoyed diabolo, a game involving balancing a spinning top on a string with two attached sticks. During the winter, Lenglen performed diabolo routines in front of large crowds on the Promenade des Anglais in Nice. Her father credited her confidence to play tennis in large stadiums to her experience as a diabolo performer.

Lenglen's father attended tennis tournaments on the Riviera circuit, where the world's best players competed in the first half of the year. Having played the sport recreationally, he bought Lenglen a racket from a toy shop in June 1910 shortly after she had turned 11 years old, and set up a makeshift court on the lawn of their house. She quickly showed enough skill to convince her father to get her a proper racket from a tennis manufacturer within a month. He then developed training exercises and played against his daughter. Three months later, Lenglen travelled to Paris to play on a proper clay court owned by her father's friend, Dr. Cizelly. At Cizelly's recommendation, she entered a local high-level tournament in Chantilly. In the singles handicap event, Lenglen won four rounds and finished in second place.

Lenglen's success at the Chantilly tournament prompted her father to train her more seriously. He studied the leading male and female players and decided to teach Lenglen the tactics from the men's game, which were more aggressive than the women's style of slowly constructing points from the baseline. When the family returned to Nice towards the end of autumn, her father arranged for her to play twice a week at the Nice Lawn Tennis Club even though children had never been allowed on the courts, and had her practise with leading male players at the club. Lenglen began training with Joseph Negro, the club's teaching professional. Negro had a wide variety of shots in his repertoire and trained Lenglen to play the same way. As Lenglen's primary coach, her father employed harsh and rigorous methods, saying, "I was a hard taskmaster, and although my advice was always well intentioned, my criticisms were at times severe, and occasionally intemperate." Lenglen's parents watched her matches and discussed her minute errors between themselves throughout, showing restraint in their criticisms only when she was sick. As a result, Lenglen became comfortable with appearing ill, which made it difficult for others to tell if she was sick.