[{quoted}](name=Slamurai Jack,realm=NA,application-id=3ErqAdtq,discussion-id=A1NXTzEp,comment-id=00010001,timestamp=2015-06-03T11:12:35.528+0000)
If you actually think that Malzahar is Yasuo's hardest matchup, you clearly don't play Yasuo much. Hell, I'd honestly say it's one of Yasuo's easier matchups compared to these champions.

Malzahar can be a pain if you haven't managed to get a lead on him before 6 or you get ganked at an inopportune time, but if you can't get a lead against Malz before 6, I don't know why you're playing Yasuo. Malz just used his E on a minion, so what is he going to do? Auto you to death? Time to all in Malz! Malz just missed his Q? All in time! Malz just used his E on you while you have a minion advantage? Guess who's about to get all inned?
Malzahar has no defensive steroid, no sustain, no escape, and only 1 targeted ability before level 6; you can pretty much all in him at will before 6 and you should be able to force him to back at least once before he gets his ult. And even once he gets his ult, there are tons of things you can do to mitigate it's effectiveness. The first and easiest is to take exhaust. Malzahar will want to use his QWE on you before ulting or else it doesn't really do much, so just exhaust him if those spells are about to hit and enjoy easily surviving his combo. Early MR or even a full hexdrinker make it impossible to 100-0 you until well later in the game. Also, if you are all inning him, save your dash onto him until he trys to cast Q. The cast time is long enough that you can easily dash onto him before it hits you, ruining his combo. And if he dares to use cooldowns on minions instead of you? All in him immediately. Also, Qss only costs 1255 now; enjoy your free lane.
You're right, I don't play much Yasuo (I have a pretty good understanding of how he works though, played him for a few months before I decided I didn't really enjoy him and went back to my main, who is conveniently Malzahar.
That said (and i'm being completely literal about this) I have NEVER lost a lane to Yasuo as Malzahar, and every time I've been in it, its been a complete stomp for me, He can't block Q (okay well he can but its really tricky to do) but the worst part is that I can just sit near the wave, and throw E on him whenever I have an adult voidling up.
6 is where the fun begins since theres nothing he can do to me anymore without rushing an item that delays his power spike (and even then, once he has it I simply don't ult him anymore)
TL;DR: Its mostly the fact that Malzahar's main form of harass (his E) is impossible to dodge, you can just poke Yasuo's shield off with a single auto anytime its up. Usually the only time Yasuo seems to be on an even playing field is level 1, when I only have Q, once I have E its pretty hard for him to CS since my voidling will zone him.
On a side note, as someone who plays Cho, how is that lane easy for him? I've always had trouble ever hitting Yasuo with Q because of his dashes