UFC light heavyweight champion Carlos Ulberg has undergone knee surgery for a torn ACL, following his title win over JiYí Procházka at UFC 327 last weekend.

Ulberg (14-1) suffered the injury during the first round of Saturday’s 205-pound championship fight in Miami. The New Zealander still managed to knock out Prochazka with a left hook, despite fighting on one leg. Ulberg posted about the surgery from Las Vegas this week, and his manager Ash Belcastro confirmed he tore his ACL to Uncrowned.

The UFC has not announced what will happen to the light heavyweight belt during Ulberg’s recovery. The promotion has had a string of unfortunate circumstances within that division, including three title vacancies in the last four years. Prochazka and Jamahal Hill vacated the belt due to injuries in 2022 and 2023, respectively. Recently, Alex Pereira vacated the belt to move up to heavyweight in February.

Immediately after his loss at UFC 327, Prochazka (32-6-1) claimed he felt “mercy” for Ulberg after the knee injury occurred in the opening round, which led to the loss. Prochazka has already called for an immediate rematch. The division’s other highly ranked contenders include former champions Magomed Ankalaev and Jan Blachowicz, and Khalil Rountree Jr.