[FEN "3rr1k1/ppp2pp1/2q4p/3b4/P1nPpN2/2P1P1BP/2Q2PP1/R2R2K1 b -"]

23... a5 24. Rdb1


w b wb bw | w b wb bw

b     an



23...a5      an



24. Rdb1      an