Emery said: "Difficult match, very tough match. A tight result and a tight match. We created chances, we conceded some chances. We took advantage today and we knew before the match it was going to be difficult.
"Now again we have to be ready there to play 90 minutes and even extra-time and penalty shootout even because we know now every match that we are playing is difficult.
"It's very important to try to control set pieces in games offensively and defensively. We have to try to be stronger in our structure because they (Lille) were sometimes threatening us more than we wanted.
"It's a good result because we won today. We know it is going to be difficult there but we have to try to get again our position on the pitch, understanding how we play today."