Eastern, Anhanguera

The Anhanguera arises when White answers the Eastern move order of the Pterodactyl Defense, 1. e4 g6 2. d4 Bg7 3. Nc3 c5, with 4. Be3. The bishop defends d4 against the combined pressure of the c5-pawn and the g7-bishop. It also declines 4. dxc5, which would let Black play ...Bxc3+ and damage White's queenside. The bishop on e3 does leave b2 without its usual guard, and White's development has to work around the knight on c3 being pinned once Black's queen reaches a5.

The usual reply, by a wide margin, is 4...cxd4. After 5. Bxd4, White's bishop meets Black's fianchettoed bishop on the long diagonal, and the game moves into open Sicilian-type positions in which Black has fianchettoed early. Black can also keep the tension. 4...Nc6 piles more pressure on d4. 4...Qb6 attacks b2 and d4 together, and in practice Black has scored well with it. The engine gives White a slight edge. Across all games, though, the results are close to even, which fits the opening's standing as an offbeat choice whose positions are decided more by familiarity than by deep theory.