Rocky Balboa fights as a southpaw (left-handed). In the second film, against Apollo Creed, he comes out orthodox and Mickey intends for him to switch back to southpaw late in the last round, but Balboa refuses saying "no tricks, I ain't switching". Mickey tells him that Apollo is ready for him (if he continues using his right) and so towards the end of the round, he does indeed lead with his left. The real reason for this is Sylvester Stallone tore his pectoral muscles in training!