Rybka screws up?

I gave this game to Rybka 3 to analyze (it was one of my OTB games) and after I played 40... Nd4 it has ?? and says that Rgc8 saves the game, giving 41. Rd3 R8c6 as +/=. I was in disbelief, thinking that I am simply dropping the knight in that line, so I put it through the Crafty program on CB8 which agreed with my belief that white is easily winning. Are Crafty and I missing something here?

Originally posted by randolph
[pgn]1.d4 e6 2.e4 d5 3.Nc3 Nf6 4.Bg5 Be7 5.e5 Nfd7 6.Bxe7 Qxe7 7.Qg4 0-0 8.Bd3 c5 9.Nf3 cxd4 10.Bxh7+ Kxh7 11.Qh5+ Kg8 12.Ng5 Qxg5 13.Qxg5 dxc3 14.bxc3 Nc6 15.f4 Nc5 16.0-0 Ne4 17.Qh5 b6 18.Rf3 Ba6 19.f5 Be2 20.Re1 Bxf3 21.gxf3 Nxc3 22.f6 Nd4 23.fxg7 Kxg7 24.Qg4+ Kh8 25.Qxd4 Rac8 26.Qh4+ Kg7 27.Qg5+ Kh7 28.Qh5+ Kg7 29.Kh1 Rg8 30.Rg1+ Kf8 31.Qh6+ Ke7 32.Qf6+ ...[text shortened]... ich agreed with my belief that white is easily winning. Are Crafty and I missing something here?

Perhaps the idea is 40...Rgc8 41.Rxb5 Rxc2 with lots of Rook checks coming - enough to draw?

Edit: My Fritz 9 sees the draw fairly quickly, once you actually force it down the 41.Rxb5 path.

Originally posted by SwissGambit
Perhaps the idea is 40...Rgc8 41.Rxb5 Rxc2 with lots of Rook checks coming - enough to draw?

Edit: My Fritz 9 sees the draw fairly quickly, once you actually force it down the 41.Rxb5 path.

Ok, thanks- I thought I had the king getting away from the checks.

Originally posted by randolph
Ok, thanks- I thought I had the king getting away from the checks.

Interesting position that highlights a queen that is stuck for good moves. In the line Rgc8 41.Rxb5 Rxc2, where can the queen go...

- obviously a1 and b1 are out due to Rc1+

- Qd4 actually prevents the king from escaping since it then can't safely cross the 4th rank: Qd4, Rc1+, Kg2, R1c2+, Kh3 (there is no escape path via Kf1-e2-etc), Rh8+ and if now Kg4, Rg2+ and Rh4+ highlights the unfortunate placing of the White queen. In other lines, Black playing Rc4 with a pin does a likewise role

- Qb3 Rd2! Notice how the White pieces are limited in their options to prevent the backrank mate. The White rook ironically keeps the Black king safe from checks. Now White has to repeat: Qb1, Rdc2

The top level mainline, Rgc8, Rd3 appears to mainline a slight advantage for White. I used Rybka 3.