I think he should start. He's the most in form of the two left backs.
I love Robbo, he will go down as a club legend, but prior to his injury he look frustrated and shot mentally. It's understandable too as he has played pretty much every game going for 4 years, with no competition for his place in his club and national team.
Think he just needs a break and now with Kostas, we can afford to give him it.