(threatening Rh4#) Nxg2 38.Rxf5 (intending Qf8+ is crushing) Rd4 38.Re1 Nxg2 Christiansen evidently felt that this gave better swindling chances than 38...Nxc4 39.c3 Nd2+ 40.Kc2 Rd8 (or 40...Nb3 41.Rd1!)