Darius vs Yasuo

Aim the outer edge of Decimate (Q): only the blade heals you and applies Hemorrhage (passive). The handle, in the center, deals less damage.

Go all-in when your target has five Hemorrhage (passive) stacks: you gain a massive AD bonus, and Noxian Guillotine (R) hits harder with each stack.

Save Apprehend (E) to pull back an enemy who retreats, not to start a trade: it's your only pull, on a 26 to 16 second cooldown.

Cast Noxian Guillotine (R) on the lowest-health target: its true damage ignores armor, and if it kills, you can recast it right away.

Hit him with a cheap attack to trigger the Way of the Wanderer (passive) shield, then start the real trade: otherwise, it absorbs your best damage.

If you have projectiles, save them for after Wind Wall (W): it blocks them all for 4 seconds, on a 25 to 17 second cooldown. Other spells go through it.

Don't stand right behind your minions: each one gives him a target for Sweeping Blade (E), and he gets closer to you with every dash.

Get out of the line of his whirlwind, the third Steel Tempest (Q): without a knock-up, he can't cast Last Breath (R).

Judge his threat by his crit items more than his level: Way of the Wanderer (passive) raises his critical strike chance, so each crit item does more for him.