Sergio Mendoza losses
Over 7 years as a professional, Sergio Mendoza has compiled a 27-1 (23) record, including three title fights across four weight classes. His only loss came in a title fight against Thanongsak Simsri.
1. Sergio Mendoza loses to Thanongsak Simsri via KO
On April 13, 2026 Sergio Mendoza fought Thanongsak Simsri for the IBF light flyweight title. Mendoza was 26 years old with a record of 27-0, and Simsri was 25 with a record of 39-1. Mendoza was on an undefeated 27-fight winning streak and Simsri was on a 15-fight winning streak. Simsri stopped Mendoza via KO in the 2nd round. Failed to capture the title.