Just days after having to withdraw from her upcoming bout, Cheyanne Buys already has her next fight booked. Montserrat Ruiz has been forced out of UFC on ESPN 31 and Buys (6-2 MMA, 1-1 UFC) will step in to face Mallory Martin (7-4 MMA, 1-2 UFC) on Dec. 4. A person with knowledge of the matchup confirmed the booking to MMA Junkie on Tuesday but asked to remain anonymous because the promotion has yet to make an official announcement. MMA Fighting was first to report the news.