The Ultimate Fighting Championship preserved its high-stakes co-main event with a rising star making a quick turnaround.

At UFC 303 on June 29, former champ Jamahal Hill (12-2) was expected to face Khalil Rountree in the co-headlining spot. Rountree was forced out of the contest due to a failed drug test, and he was issued a reduced suspension of two months plus anything the Nevada State Athletic Commission will add. In Rountree’s stead will be surging New Zealand-based force Carlos Ulberg (10-1), with news of him serving as the replacement breaking from the New Zealand Herald on Thursday. The pairing has since been confirmed by multiple outlets.

Hill is looking to rebound from a concussive defeat at the hands of Alex Pereira at UFC 300, where he fell short to reclaim his former belt. Hill snatched the vacant throne against Glover Teixeira in early 2023, capping off a four-fight win streak where he prevailed over Jimmy Crute, Johnny Walker and Thiago Santos on his way up. “Sweet Dreams” became the first fighter in company history to win a title after earning a contract on Dana White's Contender Series, doing so back on the third season when he stopped Alexander Poppeck with strikes.

“Black Jag” has not looked back since suffering his first career loss, as Kennedy Nzechukwu punched him out at UFC 259 in 2021. Since then, Ulberg has rattled off six straight wins, including five finishes with four of them taking place in Round 1. Most recently, the City Kickboxing standout smoked Alonzo Menifield in 12 seconds to record one of the quickest knockouts in divisional history, doing so in May at UFC on ESPN 56. As a pro, Ulberg posts 80% of his victories via stoppage.

UFC 303 will go down at the T-Mobile Arena in Las Vegas on June 29, with a non-title main event pitting Conor McGregor against Michael Chandler at 170 pounds. While Hill-Ulberg will be at the no. 2 spot on the lineup, the remainder of the billing has not yet been made official. Other likely main card encounters include a women’s bantamweight contest between Mayra Bueno Silva and Macy Chiasson as well as a clash at 185 pounds when Joe Pyfer fights Marc-Andre Barriault.