Position from my league game yesterday. I played 42.c5 here, which looks normal (at least to me…). Turns out that after 42…a5 I have no win and thus my move was a grave error. 43.c6 Ke8 and my pawns are stuck.
The way to win is 42.Rxh7 Rxc4 42.Rg7, winning the g-pawn.