1...Qa6+!
2.Kg2Qd6
First, Black blockades the d-pawn
3.Qd4Kg8
4.Qc4Kf7
Now the Black king aims to attack d5
5.Qb5Qd8
6.f4Qc7
7.Kf3Qc3+
8.Kg4
Clearly not 8.Ke4 Qb4+! and the pawns in this formation will win for Black
8...Ke7
9.Qb6h5+!
10.Kxh5Qh3+
11.Kg5Qg2+
12.Kf5Qxd5+
13.Kg6Qd6+!
14.Qxd6Kxd6
15.f5a4
16.Kxg7a3
And Black won
Marshall-Alekhine (1929)