ONE Championship has confirmed a major shake-up to its U.S. expansion plans, as Thai superstar Stamp Fairtex has suffered a setback while rehabilitating her surgically repaired knee. As a result, she has withdrawn from her highly anticipated ONE Women’s Atomweight MMA World Championship unification bout against Denice Zamboanga at ONE 173: Denver, originally set for August 1, 2025, at Ball Arena.

Due to the loss of this marquee matchup and the inability to secure alternate World Championship headliners, ONE Championship has rescheduled the entire event to June 26, 2026, at the same venue.

In a significant move, Stamp has also relinquished her World Title, making Denice Zamboanga the undisputed ONE Atomweight World Champion after holding the interim belt. This marks a pivotal moment in the atomweight division, as Zamboanga becomes the new face of the weight class following Stamp’s nearly two-year absence from competition due to injuries.

“We are saddened to hear of the injury setback to Stamp and wish her nothing but the best in her road to recovery,” said Chatri Sityodtong, Chairman and CEO of ONE Championship. “When bringing the world’s largest martial arts organization to the U.S., we strive to deliver the very best product to our passionate American fan base.”

ONE Championship emphasized that the U.S. remains a high-priority market, reaffirming its commitment to monthly ONE Fight Night broadcasts in U.S. primetime and more on-ground events in the future.

Fans holding tickets for the original August 1 date will be contacted by Ticketmaster and given the option of a full refund or keeping their tickets for the June 26, 2026 event. For assistance, ticket holders can email ticketing@onefc.com.

This latest development puts a pause on one of the most anticipated matchups in women’s MMA, while setting the stage for a new era under Zamboanga’s championship reign.