South African teenager Caster Semenya produced the fifth fastest 800 metres time in history to become a world champion at the age of 18 on Wednesday night, but she also found herself at the centre of a controversy over whether she is a woman or really a man.
Semenya's former headmaster said he was "very, very proud" of the dedicated runner, but admitted she reached grade 11 before he realised she was a girl.
Eric Modiba, head of the Nthema Secondary School, from where Semenya graduated last year, added: "She was always rough and played with the boys. She liked soccer and she wore pants to school. She never wore a dress. It was only in Grade 11 that I realised she's a girl."
In an interview with South Africa's Beeld newspaper, Mr Modiba explained that Semenya wore the male version of the uniform at school - the yellow shirts and grey pants. All the other girls wear reddish-brown skirts and yellow shirts.
Semenya was banned from speaking to the media following her sensational final race.
She was whisked away from the crowd within moments of claiming gold with an impressive 1.55:45 time, beating defending champion Janeth Jepkosgei of Kenya into second place and leaving British star Jennifer Meadows to collect bronze.