WSOF 23Changes Made to WSOF 23 Following Injuries To Isaac Vallie-Flagg and Kelvin Tiller José Youngs September 15, 2015 News, Spotlight, WSOF Tucson, AZ-based fighters Kamuela Kirk and Brian Grinnell have been given the shot of a lifetime after injuries have rendered Isaac Vallie-Flagg and Kelvin Tiller ineligible to compete in their respective Kirk (4-1) will replace Vallie-Flagg, who sustained an elbow injury, in the scheduled lightweight bout against former UFC veteran Estevan Payan (16-8). Meanwhile, Grinnell (8-6) will fill in for Tiller in the scheduled middleweight contest against undefeated Vagab Vagabov (19-0) of Dagestan, Russia. The 21-year-old Kirk, who will be competing his fourth start of 2015, is coming off of a first round TKO over Edgar Escarrega. To date, his only defeat, came via split decision in February. Originally from Shawnee, Okla., the 27-year-old Grinnell (8-6) has won 6 of his 8 professional career wins by way of submission. In his latest effort, a July matchup against Levi Queen, Grinnell forced his opponent to tap out in the first round. WSOF 23 is currently set to take place on Sept. 18. at Comerica Theatre in Downtown Phoenix. A lightweight championship rematch between reigning champion Justin Gaethje and Luis Palominio will serve as the main event while a light heavyweight title fight between David Branch and Teddy Holder will appear in the co-main event.