Now White's best option is to accept doubled pawns with 6.fxe3, which the Encyclopaedia of Chess Openings gives as the best move. Black gets a slight advantage, but White has avoided the worst and can defend.
Now 7.Kxf2 would lose the queen to 7...Qxd1, so White must play 7.Ke2.
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Position after 7...fxg1=N+!
7. Ke2 fxg1=N+! (diagram)
Promotion to a knight is the key to the trap. (If instead 7...fxg1=Q, then 8.Qxd8+ Kxd8 9.Rxg1 is okay for White.) Now 8.Rxg1 Bg4+ skewers White's queen, so the king must move again.
8. Ke1 Qh4+ 9. Kd2
The alternative, 9.g3, loses the h1-rook to the fork 9...Qe4+.
9... Nc6
White is hopelessly lost. After 10.Bc3, 10...Bg4 followed by 11...0-0-0+ is crushing.
In an 1899 consultation game in Moscow that involved Blumenfeld, Boyarkow, and Falk playing as White against Lasker, the players played the Lasker Trap line up through Black's fifth move. White responded to 5...dxe3 with 6.Qa4+?, but Black wins after this move also. The game continued 6...Nc6 7.Bxb4 Qh4 8.Ne2 Qxf2+ 9.Kd1 Bg4 10.Nc3 0-0-0+ 11.Bd6 cxd6 12.e6 fxe6 13.Kc1 Nf6 14.b4 d5 15.b5 Ne5 16.cxd5 Nxd5 17.Qc2 Nb4 18.Nd1+ Nxc2 19.Nxf2 Rd2 0–1 (White resigned).[2]
^Hooper & Whyld 1996 say that Dubois pointed out the trap in 1872 (p. 219). Although they do not specify where Dubois published the trap, it could refer to the three-volume work on the openings that Dubois published from 1868 to 1873 (p.116). Elsewhere they state that the Albin Countergambit was not introduced until 1881 (p. 6), which seems to be a contradiction. It is not clear if the year of discovery was 1882 instead of 1872, or if 1881 was the tournament introduction of an opening that had been published in 1872 or earlier.