Bergman, the former WBU welterweight holder, retired in 2010 with 33 knockouts in 44 wins against five losses.
"Zab was the man amongst men; he had very good hand speed and packed power too," said Bergman, who is now an official in Cairo Howarth's mixed martial arts, known as Extreme Fighting Championship.
Judah has a 23-year professional boxing career. He fought the likes of Floyd Mayweather Junior, Miguel Cotto and Kostya Tszyu.
Boxers who died after being in a coma following losses:
1980: Lupe Pintor of Mexico beat Welshman Johnny Owen for the WBC bantamweight title. Owen died six weeks later without having regained consciousness.
1982: Young Ali (Asymin Mustapha) collapsed on the way out of the ring after being knocked out by Barry McGuigan in London. He lay in a coma for several months and died in December of that year.
1982: Duk-koo Kim was carried from the ring in a coma after he was beaten by Ray Mancini for the WBA lightweight title. He died four days after the contest.
1985: Jacob Morake died after being knocked out by Brian Mitchell.
1988: Brian Baronet was in a coma for three days before dying after being knocked out by Kenny Vice.
1989: David Thio died 10 days after being knocked out by Terrence Ali.
1991: Clive Skwebu underwent brain surgery and lapsed into a coma after he was knocked out by Ndoda Mayende. Skwebu died nine days later.
2008: Samora Msopi died the morning after he was knocked out by Mfundo Gwayana at Orient Theatre, East London.
2014: Female boxer Phindile Mwelase died after failing to emerge from a two-week coma. She was knocked out in five rounds by Liz Butler in Pretoria.
2017: Herbert Nkabiti died of head injuries in hospital hours after being knocked out by Williers Baloyi. Nkabiti was rushed to the hospital and he slipped into a coma and died hours later.