After the moves 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Be2 e5 7.Nb3 Be7 8.O-O O-O 9.Be3 Be6 10.Qd2 Nbd7 11.a4 Rc8 12.a5 Qc7,
Karpov has tried both 13.Rfc1 and 13.Rfd1.
According to John Nunn's Najdorf for the Tournament Player, published in 1988, "13.Rfc1 is no longer causing problems for Black, so recent games have seen a switch to 13.Rfd1." At this point, Nunn considers only 13...Qc6, 13...Rfe8, and 13...Rfd8.
On the two occasions that I have encountered 13.Rfd1 as Black, I have played 13...Nxe4!?, a move that is not mentioned in ECO or any other opening manual.
Both games proceeded with 14.Nxe4 Qxc2 15.Qxc2 Rxc2 16.Nbd2 d5!.
From the diagram, my game against national master Saul Wanetick at Toms River in 1986 continued 17.Ng5 d4 18.Nxe6 fxe6 19.Bg4 dxe3 20.Bxe6+ Kh8 21.Bxd7 exd2 22.f3 Rxb2, and Black won in 62 moves.
Instead, my game versus candidate master John Fincken at Hamilton in 1991 saw the continuation 17.Bd3 Rxb2 18.Rdb1 Rxb1+ 19.Rxb1 dxe4 20.Bxe4 Bc5 21.Bxb7 Bxe3 22.fxe3 Nc5 23.Ne4 Nxb7 (23...Bf5!?) 24.Rxb7 Bd5 25.Rb4 Bxe4 26.Rxe4 f6 27.Rb4 f5, and Black was victorious in 61 moves.
There may be a refutation to 13...Nxe4!?. But, if one exists, why isn't it given at least a footnote in the opening books?
{This article originally appeared in Atlantic Chess News in 1992}