the variation sets a trap: if black plays along the lines of the classical variation, he gets in trouble after 3...dxe4 4.nxe4 bf5 (4...nd7 is playable) 5.ng3 bg6?! (5...bg4) 6.h4 h6 7.ne5 bh7 (7...qd6 may be best) 8.qh5! g6 (forced) 9.bc4! e6 (9...gxh5?? 10.bxf7#) 10.qe2 with a huge advantage for white. now 10...qe7! is best. instead, lasker–radsheer, 1908 and alekhine-bruce, 1938 ended quickly after, respectively, 10...bg7?? 11.nxf7! and 10...nf6?? 11.nxf7!