Found this in a game I was looking over...I thought it was pretty cool.

It's not a puzzle because there are alternate moves.I modified the position slightly. Do take a moment to think about what you'd play before clicking thru.

I saw the mate almost immediately :) the only difference is that I chose 2.Nb5

That is a nice problem though, I think the hard part is actually getting into this kind of position knowing that it is won rather than solving it

which game did you see this played in?

Any how nice end game.

Nice problem.

I think this is pretty easy if one knows the mate as you did but a good bit harder if one doesn't know well the K + N + rook pawn mate beforehand, as I didn't!  The rook pawn is so often a special-case disadvantage, but here it's got a benefit. Just goes to show, you can't know to many mating patterns.

The game was Har-Zvi v Savchenko 2007. The Black pawn, d3, was on e6 (I moved it just to give White a little something extra to think about. Maybe he needs to try to stop the d pawn from promoting?

I don't see how 1 Nb5 fails?

It doesn't fail but it isn't best, it doesn't mate cleanly as other lines that deflect the Black N to g8 do. (I should probably move that black pawn to d2 and then maybe 1.Nb5 does actually fail.) After 1.Nb5 Nd5+ black will worm out of the immediate mating net. Black can't stop the a-pawn from Queening however and  Black is still quite completely lost. I didn't mean to present this as a puzzle with a forcing solution, It isn't one. I was just intrigued with how nicely N+P+K coordinate to mate a cornered king.