Unbeaten British and Commonwealth champion George Groves's September appearance at Wembley Arena has been put in doubt by a deep cut suffered in his return on Saturday. Groves put in a strong showing against Francisco Sierra, knocking out the Mexican banger in the sixth round in an exciting display. The Hayemaker fighter was injured in the process, suffering a deep cut above his eye in a clash of heads in the second round of the bout. Groves was scheduled to headline a show promoted by Frank Warren at Wembley Arena on September 14, most likely against domestic rival Kenny Anderson. The cut may take a number of weeks to heal, putting a return fight in the capital in some jeopardy. Groves's knockout win in San Jose, California improved Saint's unbeaten record to 15-0.