Oleksandr Gvozdyk, the former world light-heavyweight champion who lost to Artur Beterbiev by TKO on Friday, was released from hospital on Sunday after staying two nights as a precaution.
Gvozdyk, 32, was stopped in the 10th round of an action-packed 175-pound unification bouton Friday at the Liacouras Center in Philadelphia.
Referee Gary Rosato waved off the fight after two minutes and 49 seconds of the 10th after Beterbiev (15-0, 15 KOs) dropped an exhausted Gvozdyk (17-1, 14 KOs) three times.
According to ESPN, Gvozdyk walked alongside trainer Teddy Atlas to an ambulance to make the short trip to the hospital to be checked out as a precaution.
Atlas confirmed he stayed with Gvozdyk a second night to be safe before the 32-year-old was released with a minor concussion.
"All is clear," Atlas told ESPN. "No [brain] bleed or anything. Thank God, just a minor concussion from the hits to the back of the head they said, but we needed to be sure."
Gvozdyk, a Ukrainian who is based in California, won his WBC title in December 2018 - stopping Adonis Stevenson in a bout that saw the long-reigning champion put in an induced coma and treated for a traumatic brain injury - and made one successful defence before being stopped by the undefeated Beterbiev on Friday.
A Russian based in Montreal, Beterbiev, 34, defended his IBF title for the third time since winning it in November 2017.