The 41-year-old was put on a stretcher and rushed to hospital after the devastating knockout in the 11th-round of the title fight.
The Canadian's five year reign as WBC light-heavyweight champion came to an end as he suffered the second defeat of his career.
He was left slumped on the canvas after an explosive barrage of punches from the unbeaten Ukrainian.
And his promoter, Yvon Michel, gave fans an update about his condition in the night.
He said: "News on the condition of Adonis. The family of Adonis and Yvon Michel are currently with Adonis Stevenson.
"They want to inform friends and supporters Adonis is currently in critical condition in intensive care, at the hospital, following his fight against Oleksander Gvozdyk.
"They appreciate the concern and support of everyone.
"There will be no further comments at this time and they respectfully request your understand in their desire to stay private."
Tributes have poured in from around the world, with fans praying for him to make a speedy recovery.
The World Boxing Council said: "The WBC and boxing community from the world join in prayers for the safe recovery of our dear friend, great fighter and exemplary human being @AdonisSuperman.
"May God provide the strength to overcome this unfortunate set back."
Gvozdyk moved to 16-0 as Superman, who beat Tony Bellew in 2013, dropped to 29-2-1 with his first since loss since 2010.
Source: Read Full Article