If only things were that easy Anthony (you forgot the white knight on c3)
Alekhine Defense: Seirawan's Line?

Hi Ray,
Seirawn obviously wants his reader to get out of the beaten paths early with a relatively sound variation: a good way to prepare for live chess. I think c5!? is sound but leads to too many simplifications to be a big threat in slow chess.com games.
8..Nbd7 is better for Black than the Queen exchange, followed by Nbd7 because of 11.Nd5!
If 8...Nbd7; 9. Bc4 00; 10. Nf3 Qa5 11. 00 the game could get pretty lively if Black gets greedy.
Let's talk about it Thursday or Saturday!

Sierawan has published several decent books, however i think this one is crap. Waste of $50 (australia has the worst prices for chessbooks in the world because Ian Rogers books don't seem to be sold).

I think that if your database contains only one master game on this, then you have your answer. If masters don't play 8.c5, then maybe you shouldn't either. I'm not saying don't experiment in the opening, but if you don't have a feel for the line and there are no master games to guide you, then I recommend giving this line up. Practise against a computer a bit (taking both sides) until you get it settled in your soul how you feel about this is about the best advice I can give you. But there are much better lines against Alehine's than this.
Are there any Alekhine experts who can explain move 8? I am wary of a recommended line, even if from such a high-caliber GM, that appears to never have been used by other masters. In my personal game, I played the position poorly and my opponent (boneyard) crushed me. I wish I could just say it was his name that intimidated me. Rather, I made a bunch of bad move, never took advantage of my lead in development and space, and the overextended c5 pawn created a weakness I couldn't fix. Blah.