Mini Chess

White to play and force the black king to d3.

1. Qc3+ Ka2 2. Qc1 Kb3 3. Qa1 Kc2 4. Qa2+ Kc3 5. Qb1 Kd2 6. Qb2+ Kd1 7. Qa2 Kc1 8. Qb3 Kd2 9. Qb1 Kc3 10. Qa2 Kd3

If 4. … Kc1, then 5. Qb3 and we get to the position in move 8. If 4. … Kd1, then 5. Qb1 Kd2 6. Qb2+ and we get to the position in move 6.