ECO B33 & B44

A couple of small, related questions about the first game of the 1971 Fischer - Petrosian Candidates Final have been on my mind for some time, so I'm going to spend two blog posts to address them. The first question involves the difference between the line played in that game and the Sveshnikov variation (see Sveshnikov or Chelyabinsk? for some background on the moves and the name of the variation). I often play against the Sveshnikov as White and have remarked on the similarity between it and the opening of the Fischer - Petrosian game. What exactly is the difference?

The Sveshnikov goes like this: 1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 e5 6.Ndb5 d6 7.Bg5 a6 8.Na3 b5. Fischer - Petrosian went like this: 1.e4 c5 2.Nf3 e6 3.d4 cxd4 4.Nxd4 Nc6 (2...e6 and 4...Nc6 can be interchanged) 5.Nb5 d6 6.Bf4 e5 7.Be3 Nf6 8.Bg5. The following graphic compares side-by-side the resulting positions in the two variations.

The most significant difference between the two positions is that the players have taken an extra move pair in the position on the right, but White has played one move less (Nc3) than in the position on the left. How did this happen?

A comparison of the moves shows that, in Fischer - Petrosian, Black's e-Pawn took two moves to advance to e5, while White's Bishop took three moves to get to g5. That accounts both for the extra move pair and for White's lost tempo. As I've noted in the diagram, the Sveshnikov is ECO B33. Fischer - Petrosian is ECO B44.

If only all questions about openings were so easy to answer. I'll tackle the second of my two questions in a future post.