User blog comment:AtheistUntoDeath/Which of these Champions would win? Part 5/@comment-2010873-20140530063941

Assuming full build. Both are lvl 18 and build typical glass cannon, Yi with Youmuu's, IE, Beserker's boots, LW, BOTRK, Statick Shiv and Yasuo with Statick Shiv, Beserker's boots, BORTK, IE, LW, (any 6th item)

This is a skill matchup; whether Yasuo lands his Q-tornado, and whether Yi can juke the tornado.

If Yasuo ults Yi, Yi will 100% lose the fight since Yi will take damage without being able to counterattack and Yasuo will regain his shield.

I would say this favors Yi since Yi's DPS should be higher (although due to Yasuo's reliable 100% crit mechanic it's hard to really say) and it's easier for Yi to juke the tornado with his Q, depriving Yasuo of valuable CC and burst damage from his ult.