Born in Pesaro, she started playing rugby as a centre; she then moved to Mira to play for Brenta Riviera, she converted to second row and subsequently to prop; she won the national title in her debut season for her new club and, at the same time, made her test debut for the national team in the 2009 FIRA Women's Trophy aged 18.[1][2]
Returning to Pesaro in 2010, she confirmed her place as a regular in the Italian team that took part in the 2011 Six Nations. She returned to Brenta Riviera for a second time in 2011. In 2016 she moved to Valsugana in Padua to finish her studies in motor sciences at the local university. She won two more championships with Valsugana in 2016 and 2017.
Gai joined French club, Rennes, in 2017. She competed at the 2017 Women's Rugby World Cup in Ireland with the national team where they reached ninth place overall.
During the 2024 Six Nations match against Wales, Gai became only the second Italian woman to become a centurion.[1][3]
