Jack Della Maddalena broke his left arm "early" in his UFC 299 fight against Gilbert Burns, his manager Tim Simpson confirmed Tuesday.
The welterweight contender rallied to knock out Burns late in the third round on last weekend's main card in Miami.
Simpson posted a photo of Della Maddalena's X-ray on Instagram.
Della Maddalena was in pain after the fight but only found out Tuesday that his arm was broken, according to MMA reporter Ariel Helwani. A timetable for his return has yet to be determined.
Two judges had Burns up 20-18 heading into the third round, but Della Maddalena finished "Durinho" with a knee and ground-and-pound with 77 seconds left in the fight.
Della Maddalena, a 27-year-old Australian who has been a top up-and-comer since his UFC debut in 2022, cracked the top five at welterweight with the victory over Burns, a former title challenger. Della Maddalena is 7-0 in the UFC.