In 1925, Caballero's skills were put to the test. His PC commander in Camp Ketley, Dansalan, Lanao del Sur (now Marawi City), needed a bodyguard who was skilful in Eskrima. Caballero applied for the position, but another known Eskrima fighter from llocos Sur by the name of Juan Carolla also wanted the post. Carolla's feats in arnis were also considered legendary. Since the PC commander needed only one body guard, a duel to determine the better fighter was agreed upon. In the first round, Carolla was hit in the head which made him collapse and unable to continue on with the fight, giving Caballero the victory. However, a rematch was scheduled for the following day and again Carolla was hit in the head, confirming Caballero's superior skills over his opponent. Carolla finally conceded in defeat and bowed to Caballero in respect.