A trap in the Richter-Veresov

The Richter-Veresov Attack (1.d4 d5 2.Nc3 Nf6 3.Bg5 or 1.d4 Nf6 2.Nc3 d5 3.Bg5) is the mirror image of the Ruy Lopez. It's generally considered harmless, but, as I discovered in an Internet blitz game today, that doesn't mean that Black can afford to be careless. After 3...Bf5 4.f3, White hopes to expand in the center with 5.e4. Black's most popular response is 4...Nbd7; 4...Bg6 and 4...c6 are also playable. If I got this position again, I'd probably play 4...c5, which is a little unusual but scores well. I was surprised to discover that the natural 4...e6 is a fatal blunder! After simply 5.e4! (see diagram) White wins a piece, e.g. 5...dxe4 (5...Bg6 6.e5 is similar) 6.fxe4 and now (a) 6...Bxe4 7.Nxe4 Nxe4?? 8.Bxd8; (b) 6...Bg6 7.e5 h6 8.Bh4! and Black's usual rejoinder, 8...g5, is illegal; (c) 6...h6 7.Bxf6 Qxf6 8.exf5; (d) 6...Bg4 7.Bxf6! and White will end up a piece ahead after either 7...Qxf6 8.Qxg4 or 7...Bxd1 8.Bxd8. In our illustrative game, Black resigned after 7.Bxf6; in my blitz game, I soldiered on with 7...Qxf6 8.Qxg4 Qxd4 with a dead-lost position that I eventually won.

I was surprised to learn that Milan Vukevich, who later immigrated to the United States and became an International Master, once played 4...e6?? in a Yugoslav Championship! His opponent responded with 5.Qd2?? and eventually drew.