Amanda Nunes, the pound-for-pound best female fighter in the UFC, will have to wait a little longer for the next defense of her bantamweight championship.

She tested positive for COVID-19, UFC chief business officer Hunter Campbell told ESPN on Thursday, canceling her fight with Julianna Peña that was scheduled for Aug. 7 in Houston in the co-main event of UFC 265.

Campbell said the plan is to reschedule the bout when Nunes is fully healthy and ready to compete. Nunes (21-7), 33, also holds the UFC’s featherweight championship. The fighter from Brazil is coming off a March tap-out victory over Megan Anderson.

Pena (11-4), UFC’s No. 5 bantamweight, scored a third-round submission victory over Sara McMann in January. The 31-year-old American’s two UFC defeats came against Valentina Shevchenko and Germaine de Randamie.