Dear Demetrio,
How so?If the boxer punches for example a right hander to the face /body, MOVE TO DEAD SIDE{ [by irimi /tenkan ]-EVASION.Control wrist /forearm of attacker FIRMLY and ATTACK the ONCOMING ELBOW JOINT.[- Control ]IF A BODY SHOT [Chudan ]keep close to the guy, on the deadside. If Jodan , vary the move and take the guy over [in this case ] your left shoulder ,.Make strong atemi as you enter this disturbs the boxers rhythm[ if possible use a premptive strike .You cannot afford to let a boxer take the initiative and set you up.Too dangerous.Timing / maai and good spirit is required here.Formula::Complete Evasion/Control/Atemi then execute Waza. Cheers, Joe.