Don't you have W?
You know that R has basically the same animation of her auto attack right? If you can't run away with W because you wasted it engaging (or running away from someone), your suport is roaming other lanes/you are in the frontline ( bad positioning) , Yii get's to smack you.
He still has to WALK to you and you get 2 free hits and E if he doesn't Q. BAIT his Q. Highlander has a small window of efficiency.
Any champion can smack you and outplay if you made poor decisions or panicked.
Oh and a tip. Tristanas R sometimes bugs master YI Q , sending him flying off across the map. Sometimes it proc the damage even when he is invencible (same as fiora). There are lots of skills that do that, resulting in being killed DURING an alpha strike, don't need to be a point and click one, AOE damage deals it too, making him even more squishy.
Yi excels in DUELS. He is awful in TFs ( If the other team is good = protect the ADC and APC). , laning and can get counter jungled.
Let him be good at one thing.