Right back Peter Kioso is currently the most at-risk United player, having accumulated four bookings already this season.
Kioso picked up his fourth caution during the draw at Portsmouth earlier this month, and U’s head coach Des Buckingham admitted that the decision to withdraw him for Hidde ter Avest in the final quarter of an hour at Sunderland was to avoid Kioso picking up a potential yellow card.
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Sky Bet Championship sides have until the 19-game mark to avoid picking up five bookings, otherwise players are suspended for one match.
Tyler Goodrham has been booked three times this season, plus once in the Carabao Cup victory over Peterborough United. Yellow cards in cup competitions are treated separately though.
United skipper Elliott Moore has been booked twice this season, joining midfield quartet Idris El Mizouni, Ruben Rodrigues, Louie Sibley and Will Vaulks on two yellow cards.
Defensive trio Joe Bennett, Ciaron Brown and Ben Nelson, plus Malcolm Ebiowei, Mark Harris and Dane Scarlett are the U’s players to have been cautioned once so far this campaign.