Cassano was born in Bari and his father left the family shortly thereafter. He was raised in poverty by his mother in the San Nicola district of the "Bari Vecchia" neighbourhood, and began playing football on the streets at an early age. Cassano was spotted by a Bari scout and brought up through the team's youth system, and he made his Serie A debut for Bari against local rivals Lecce on 11 December 1999. During his time with Bari, he soon emerged as one of Serie A's most promising young Italian players, drawing particular attention to himself after scoring a notable, individual, match-winning goal (his first ever Serie A goal) in a 2–1 home win over Italian giants Inter Milan, on 18 December 1999, at the age of 17: in the 88th minute, after controlling a 40-yard lobbed pass on the run with his backheel, he subsequently dribbled past veteran defenders Christian Panucci and Laurent Blanc, wrong-footing goalkeeper Fabrizio Ferron with a dummy, before finishing at the near post. Cassano's technical skill, precocious talent and impressive performances earned him the nicknames ""Fantantonio", due to his flair and creativity, and "El Pibe de Bari"" ("The Kid from Bari"), a reference to the legendary Diego Maradona's nickname, "El Pibe de Oro". During his two seasons with Bari, he scored a total of 6 goals in 48 Serie A matches, scoring 3 goals in 21 appearances during his first season, and 3 goals in 27 league matches during his second season with the club.