British boxers David Haye and Dereck Chisora are suspected of committing offences that could carry prison sentences following their Munich brawl.
German prosecutors have told the BBC that Haye is suspected of grievous bodily harm - a crime which, if proven, carries a prison sentence of six months to 10 years.
Chisora, who admitted his behaviour was "inexcusable", is under suspicion of malicious injury, which carries a jail sentence of up to five years, and making a "threat".
Haye and Chisora clashed after Chisora's defeat by defending WBC heavyweight champion Vitali Klitschko.
Police action aside, the general secretary of the British Boxing Board of Control Robert Smith says Chisora could face a life ban.