Weinsbach Defense

The Weinsbach Defense meets 4. f3 with 4...e6, declining to take on f3. Rather than defend the extra pawn, Black opens the diagonal of the f8-bishop, eyeing a pin with ...Bb4, and prepares central counterplay. The cost is a passive c8-bishop and a pawn on e4 that White can simply recover. It is the second most popular way to decline the gambit after the Vienna Defense. The engine rates the position as roughly balanced, though White scores well in practice.

By far the most common reply is 5. fxe4, the Pfrang Gambit, which restores material equality and gives White a broad center with the half-open f-file. Black can strike at that center with 5...c5 or 5...e5, but 5...Bb4 is the usual choice. After 6. a3 Bxc3+ 7. bxc3 the game transposes to a line of the Winckelmann-Reimer Gambit that is considered favorable for White. On 6. Bd3 instead, Black can try 6...Nxe4. Then 7. Bxe4 allows a queen fork of White's king and bishop, so 7. Ne2 is the better reply. Less common alternatives at move five are 5. Bg5 and 5. Be3, which keep developing and leave the e4-pawn for later.