Flawed Combination

Yesterday, I played what I thought was a nice forcing sequence and my opponent resigned. After showing it to some some students and posting the position on Chess Skill's Facebook page, I looked at chessdotcom's game analysis and was surprised. "Coach" was critical.

In the following position, Black blundered to give me a clear advantage.

Black to move

8...Nge7??

Black could have played 8...Bb4+ 9.Bd2 Nge7 with a clear advantage. After the blunder, I spent a little more than half a minute working out the combination that led to my opponent's resignation. But, we both missed a resource.

9.Qxf7+!?

"Coach" opined: "Curious move. Maybe not exactly what the position demands -- but an interesting idea."

9...Qxf7?

9...Kd8 was more stubborn, shows the flaw in my idea, but still leads to a winning advantage for White.

White to move

Analysis diagram after 9...Kd8

White now should proceed with normal development, such as Be3 or O-O. Black's king remains in the middle and White's pieces are far more mobile. But, the win of the rook through a knight fork does not occur.

Going back a move, White could have played 9.Qd6!

Black to move

Analysis diagram after 9.Qd6!

After the superior 9.Qd6, the engine favors 9...Rh7 when White wins the other rook with 10.Nc7+ Kd8 11.Qxf6 gxf6 12.Nxa8.

9...Qxd6 leads to the same position as occurred in the game.

After my 9.Qxf7, Black followed the line I had analyzed with 9...Qxf7.

White to move

10.Nd6+ Kd8 11.Nxf7+ 1-0

As he is losing the rook and cannot trap the knight, Black resigned.