Classical Variation, Greco Gambit, Main Line

The Main Line of the Greco Gambit arises when Black meets 8. O-O with 8...Bxc3 instead of 8...Nxc3, the Greco Variation. Castling has unpinned the c3-knight, so the knight on e4 is attacked. A retreat would invite trouble on the open e-file. Capturing first with the bishop means that, once the exchanges are complete, no black piece is left hanging. Black then has time for ...d5, which shuts out the c4-bishop and props up the e4-knight, at the cost of the bishop pair. The line descends from Greco's treatment of 7. Nc3 in the early seventeenth century.

White now chooses how to continue. The natural recapture 9. bxc3 is the most frequent choice. It leaves White a pawn down but with two bishops and pressure along the e-file while Black's king is still in the center. The alternative 9. d5 leaves the bishop en prise and hits the c6-knight. This is the Moeller-Therkatz Attack, also called the Møller Attack, which flourished around 1900 but is now regarded as refuted. 9. Qb3 is rarely seen. The engine rates the position as roughly level, and Black scores somewhat better in online play.