user12179: After a brief study over the exchange variation in the Alekhine's defence, On the fifth move Black can choose an extremely sharp line with e5 but i couldn't find it anywhere explained as either a bad or good move or even played.

user12402: It's losing for Black because 6.c5 N(6)-d7 7. dxe!  Black can't capture the pawn on e5 because 8. f4! wins a piece (e.g., 8. ... Nd7 9. Qe2+) so Black must play 7. Nxc5 and after 8. Bf4 White's pawn on d6 is a dagger in Black's heart.  The chess engines say White is winning.

12179: <p>After a brief study over the exchange variation in the Alekhine's defence, On the fifth move Black can choose an extremely sharp line with e5 but i couldn't find it anywhere explained as either a bad or good move or even played.</p>
 12402: <p>It's losing for Black because 6.c5 N(6)-d7 7. dxe!  Black can't capture the pawn on e5 because 8. f4! wins a piece (e.g., 8. ... Nd7 9. Qe2+) so Black must play 7. Nxc5 and after 8. Bf4 White's pawn on d6 is a dagger in Black's heart.  The chess engines say White is winning.</p>
