Surprise win from a lost position

In the original game I didn’t see the win. I was fine and the game balanced until move 11. The position here is after 21. Qa7-c5??. Black to move and win. I’m wondering if this is a common pattern (i.e. trivial to spot?). I’m still very much learning .

(first time posting here and I can’t preview my post, so I hope it shows up as puzzle (edit, figured it out. Full annotated game is here in case you’re interested)

https://www.chess.com/a/crKekUJi9zer

It's a pretty obvious idea but spotting it In a rapid game is a challenge. Your mate was good.

But you are right. You were dead lost.  Looking at your game, there are  numerous other "trivial" moves you missed which should have been much easier to spot than a mate in 9.

• How could you miss that your a pawn was hanging?
• What was the point of leaving your knight hanging on g4? Taking the c pawn?
• Did you worry at all that taking the c pawn opened up a freeway to your king?

> How could you miss that your a pawn was hanging?

I an opportunity where I hoped that knight and queen, plus opened g file (I didn’t have clear idea how yet) for rook I could force mate or at least wreak some havoc. It was a gamble for sure as my opponent had a similar idea. Right after, I found it was a terrible idea (even though in the end it worked).

> What was the point of leaving your knight hanging on g4? Taking the c pawn?

 I figured I could trade the knight for three pawns, the c, d and e pawns, which again was a bit of a gamble as it was defendable by my opponent. If successful It would also put my queen in a position close to my opponent’s king.

> Did you worry at all that taking the c pawn opened up a freeway to your king?

Yes, I was very worried, but also hoped that it would blind my opponent into thinking I’m basically defeated. My focus was the pinned g pawn (pinned by the rook) allowing me to attack.

Still, my calculations were off as I didn’t see it and moved one rook to defend on the c file pawn. As you noticed this was unnecessary as forced mate was there the moment my opponent did 21. Qc5??. I thought I’d lost, even though I actually had a winning position.

After 22. Rc4?? I saw (or thought I saw) the possible mate and with 22 .... Qxf3!! taking the knight, the game was over. I normally don’t try to play so risky, but I’m also still very much learning .

Thanks for your thoughts and insights. If my opponent hadn’t been blinded by collecting all his pieces on the c file, he needed but one other move to prevent disaster, this time I was lucky (and that for a game that isn’t about luck!).

But yeah, in hindsight this was a terrible plan with too many buts and ifs...

Lol, only now I’m realising I could’ve totally lost my queen there. Certainly didn’t see i trapped my own Q after 16.... Qxc2. Crazy bad!