Young Bulgarian boxer Isus Velichkov has died after collapsing in the ring.
Velichkov, 21, began staggering in the fifth round of a contest against Ardit Murja at a show in Albania at the weekend before falling to the ground in his corner.
The fight was immediately called off as medical teams rushed to help.
The featherweight was taken to hospital but could not be resuscitated.
According to Albanian television he suffered a cardiac arrest.
Boxing chiefs WBC have paid tribute, saying the sport was "in deepest sorrow".
The WBC released a statement on their website after the tragic news broke.
It read: "The World Boxing Council and its President Mauricio Sulaiman, lament the death of 21-year-old Bulgarian fighter Isus Velichkov.
"Although the ring doctors did their best to save his life, the death was almost immediate.
"The entire WBC joins Velichkov’s family at this very sad time, in deepest sorrow."
Velichkov was fighting his fifth professional contest, having lost his previous four.
According to Boxing Scene , he had gone the distance in all four previous fights and did not appear to have been overmatched in any of them.
His opponent Ardit Murja had won four of his previous five fights.
In July, two boxers died within a week from injuries sustained during fights.
Argentine Hugo Santillan, 23, suffered kidney failure and was in a coma after collapsing following his drawn contest with Eduardo Javier Abreu. The cause of death was recorded as heart failure.
Maxim Dadashev, 28, was left fighting for his life with "severe brain damage" following his defeat to Subriel Matias.
The Russian underwent emergency surgery to have the right side of his skull removed in an attempt to reduce the brain swelling but could not be saved.
His trainer Buddy McGirt had pleaded with Dadashev to stop before the fight was eventually called off.
