The above position is the Ruy Lopez, Modern Steinitz variation. In looking up a chess opening database I found no games where black's next move was 6...Nxe4. Is there some obvious flaw from playing this move that makes it completely unplayed? I don't understand why its never been played!

6... Nxe4? 7. d5 b5 8. Bc2.

aha! thanks!

What about 7. d5 Nc5?

viswanathan: 8: PxN NxB 9: QxN.  White still wins a piece.

oops.. I missed that.. thanks!