He had been very good recently but I don't think last night was a great performance.
He had a few of those lapses in concentration that he showed earlier in the season e.g. dangerous giveaway when passing from back in 1st half, compleletly lost his man when defending a corner in 2nd half which Matuidi did well to toe away from the attacker, positioning and switched off in the situation that ended up with Olympiakos hitting the bar.
He has certainly improved and seems like a player that needs the pressure of a big game to force him to concentrate for 90 mins, he certainly did vs Napoli and Barcelona.