Zeller Defense

The Zeller Defense, 3...Bf5, is the most frequently chosen deviation from the main lines of the Blackmar-Diemer Gambit. Instead of developing the knight with 3...Nf6, Black brings the light-squared bishop out to protect the e4-pawn, which keeps White's king's knight and bishop off f3 and d3. White usually answers 4. f3, by far the most common move. After 4...exf3 5. Qxf3 the queen hits both the bishop and b7. Black normally defends with 5...Qc8, and 6. Bc4 follows, with either 6...Nf6 7. Bg5 or 6...e6 7. g4. The grab 5...Bxc2? is poor because of 6. Qxb7 Nd7 7. Nb5 Rc8 8. Nxa7. For this reason 4...Nf6 is often preferred, transposing to the Vienna Defense. The continuation 4. f3 Nf6 5. Bc4 there is the Soller Attack.

Engines rate 4. g4 highest, chasing the bishop and preparing h4 and h5 to keep Black on the defensive. After 4. g4 Bg6 5. Qe2 the Torning Gambit arises, in which 5...Qxd4 6. Qb5+ gives White good play. The engine assessment is close to level, and White scores somewhat better than Black in online games.