Tributes are pouring in for Russian boxer Maxim Dadashev who died following injuries suffered in his IBF light-welterweight fight against Subriel Matias.
The 28-year-old collapsed in front of fans as he made his way out of the arena at the MGM National Harbor in Maryland on Friday.
He was taken to hospital with bleeding on the brain and failed to recover despite undergoing emergency surgery.
Dadashev had a 13-0 unbeaten record ahead of his fight with Puerto Rican Matias.
Russian Boxing Federation secretary general Umar Kremlev said his organisation will begin an investigation "into the circumstances that led to the death."