▁East ▁will ▁win ▁and ▁lead ▁his ▁tr ump , ▁killing ▁the ▁cross ru ff . ▁ ▁East ▁does ▁not ▁threaten ▁to ▁take ▁a ▁tr ump ▁trick , ▁just ▁to ▁lead ▁his ▁tr ump ▁and ▁stop ▁dummy ' s ▁r uff . ▁ ▁But ▁if ▁East ▁gives ▁up ▁his ▁guard ▁in ▁either ▁minor , ▁he ▁gives ▁South ▁an ▁additional ▁trick ▁in ▁the ▁side ▁suit , ▁and ▁now ▁South ▁no ▁longer ▁needs ▁the ▁r uff . ▁ ▁Notice ▁the ▁entry - sh ifting ▁mechanism ▁in ▁the ▁tr ump ▁suit . ▁South ▁cho oses ▁the ▁card ▁to ▁r uff ▁with ▁depending ▁on ▁East ' s ▁disc ard . ▁If ▁East ▁disc ards ▁a ▁diam ond ▁on ▁the ▁ 7 , ▁South ▁r uff s ▁high ▁so ▁that ▁he ▁can ▁later ▁win ▁a ▁tr ump ▁trick ▁with ▁the ▁ 1 0 . ▁If ▁East ▁disc ards ▁a ▁club ▁on ▁the ▁ 7 , ▁South ▁r uff s ▁low ▁so ▁that ▁he ▁can ▁later ▁win ▁the ▁J . ▁ ▁Example ▁ 2 ▁ ▁A ▁position al ▁s que e ze ▁can ▁ent ail ▁an ▁entry - shift , ▁and ▁in ▁fact ▁the ▁s que e ze ▁given ▁above ▁is ▁position al ▁— ▁it ▁will ▁not ▁operate ▁if ▁the ▁East - West ▁hands ▁are ▁switched . ▁But ▁many ▁knock out ▁s que ez es ▁are ▁not ▁position al ▁but ▁automatic ▁— ▁that ▁is , ▁the ▁thre ats ▁are ▁located ▁such ▁that ▁the ▁s que e ze ▁oper ates ▁against ▁either ▁oppon ent . ▁Here ▁is ▁an ▁example : ▁