Hi.

I played through the game mentioned (Portisch - Reshevsky, Petropolis Interzonal 1973), nice game indeed.

I found five subsequent games with 10...a5 where Black - as stated - have a good score (1 White win, 2 draws and 2 Black wins) where the draws and the Black wins are the most recent.

A comment can be however that in none of these games did White follow Portisch development scheme of Rac1, Qc2, f4, b3, Kh1, f5 ... .

Instead White varied with moves like Rfe1 and/or Nd5 or b4 without moving the a-rook to c1 first. 

Cheers / Anders

Hi.

The same evaluation is made also in Donaldson &  Silmans "Accelerated Dragons".  There 6...Nxd4 is given a ?! with the explanation that

"Perhaps 90 % of all games in this line see the move 6....d6 before the exchange on d4.  Why? For one thing it avoids the line 6.... Nxd4 7.Qxd4 d6 9.c5, though that has never really been to fearsome.  More to the point is that it makes White choose between Be2 and f3 to cover g4.  Ideally White would like to play Bd3 and f4.  By playing 6... d6 Black can avoid this.
"

In the recent Tiviakov ChessBase CD on the Accelerated Dragon the move-order given is 6…d6 and 7… Nxd4.   

Also if one run a dossier-report (MegaBase 2007) on Tiviakov there are 57 instances of 6…d6 and none of 6….Nxd4.

One thought is that 6…Nxd4 could be a one-off-way of avoiding the 7. Nc2 variation which is topical at the moment (recommended by Nielsen in "eXperts vs. the Sicilian").   As Almasi normally plays 7.Be2 that does however perhaps not seem so likely. 

Input-error?

Cheers / Anders

Ps.
Kylemeister - could you be more specific about the games you mentioned?

I'm seeing on line (http://www.ippogrifoscacchi.it/) the game  Almasi, Z-Tiviakov   Reggio Emilia 2007

1. e4 c5  2. Nf3 Nc6  3. d4 cxd4  4. Cxd4 g6  5. c4 Nf6  6. Nc3 Nxd4  7. Qxd4 d6  8. Be2 Bg7

In the "Accelerated Dragon" P.H. Nielsen says that  6... Nxd4?!  is an inaccurate move order  quoting a game  Polugayevsky-Jansa Sochi 1974  7. Qxd4 d6  8. Bg5! Bg7  9. Qd2 0-0  10. Bd3!
and the game is a little bit passive for B.

There is some improvements to make the 6.., Nxd4 line playable for B.?