"It's very frustrating. To be leading 1-0 at home, controlling the game and looking very comfortable, but then coming off the pitch with nothing is a bitter pill to swallow," said the Liverpool midfielder.
"In the last 20 minutes, we really did throw everything at them. We created some good chances and played some good attacking, fast-flowing football.
"But unfortunately, that five-minute spell really, really cost us and we'll have to learn from it going into our next European encounter.
"If you look at the game, there certainly were positives to take - it was just the cheap goals we gave away that is probably our one and only disappointment.
"That's football for you. It's a ruthless game and you get punished if you take your eye off the ball even if just for one second."