Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bb5/3...f5/4. Nc3/4...fxe4/5. Nxe4/5...d5/6. Nxe5/6...dxe4/7. Nxc6/7...Qd5/8. c4/8...Qd6/9. Nxa7/9...Bd7/10. Qh5

Ruy Lopez, Schliemann Defence

	a	b	c	d	e	f	g	h
8									8
7									7
6									6
5									5
4									4
3									3
2									2
1									1
	a	b	c	d	e	f	g	h

Common moves:
10...g6 - only move

Black doesn't have an obvious way of escaping the check. 10...Qg6 would allow White with her next two moves Qxg6 and Bxd7 to a) ruin Black's pawns, b) swap off material when ahead and c) prevent Black castling. Fleeing to either d8 or e7 with the king followed by 11.Bxd7 Kxd7 12.Qb5+ would ship yet another pawn, as would 10...Ke7 11.Bxd7 Qxd7 12.Qe5+. The computer recommends 10...Kd8 11.Bxd7 Qxd7 as the least bad option, although White could then swing the queen over to a5 threatening Nc6+ and so forcing the king straight back to e8, while potentially saving a tempo by not having to move the knight immediately.

So the modern, active way of defending this position as Black is with 10...g6 followed by 11.Bxd7+ Qxd7!? It doesn't sacrifice a whole rook, "only" an exchange, because White hasn't got time to capture on h8 and also save the knight.