Showalter Variation

The Showalter Variation, also called the Two Knights Variation, arises after 1. d4 d5 2. c4 dxc4 3. Nf3 Nf6 4. Nc3. The quieter 4. e3 prepares Bxc4 at once. Here White instead brings out the queen's knight and adds support to the e4 advance, postponing the recovery of the pawn. That gives Black time to hold c4. After 4...a6 5. e4 b5 Black keeps the extra material, and White is playing a real gambit, relying on a broad center and quicker development. The engine rates the position as balanced and prefers 4...a6, 4...c6 and 4...e6. The line is named after Jackson Showalter, a four-time U.S. Champion.

In practice 4...c6, preparing ...b5, is by far the most common answer. It leads to the Slav Defense: Two Knights Attack. 4...e6 transposes to the Vienna Variation of the Queen's Gambit Declined: Three Knights. 4...Nc6 reaches the Modern Gambit of the Chigorin Defense, and 4...Bg4 pins the knight on f3. In online games White scores well against each of these replies.