White is virtually forced to set a Pawn on KKt3(g3)
to relieve check and dislodge the queen on KR4(h4) [else only
4.K-K2??..QxKP++mate].
W-Alt. Black's Queen captures White's rear KP on
K5(e4) with check, forking White's doomed king's rook.
White Black
1. P-K4 P-K4
2. P-KB4 B-B4
3. PxP?? Q-R5 ch
4. P-Kt3 QxKP ch