Oh boy. If something snuck up behind her, then she must really be getting rusty. Shepard, after a quick look behind her, quickly backpedals to Yu and readies her Revenant, not about to be outgunned anytime soon.

"Heh, got me there. I'll give you all the covering fire you need." She smirks a little in return as she starts spraying the vicinity with the machine gun; any Shadows caught are in for a world of hurt.