Liverpool boss Jurgen Klopp was frustrated after defeating Roma 5-2 in the first-leg of their Champions League semifinal.
Mohamed Salah, who has now scored 43 goals since his summer move from Roma, scored twice and assisted two other goals.
He curled his first into the top corner from the edge of the box - then clipped the ball over Alisson for a second. Salah then ran down the right and squared for Sadio Mane to make it 3-0 - before doing the same to set up Roberto Firmino. Firmino then headed in a fifth following James Milner's corner.
Roma fought back as first Edin Dzeko lashed home from Radja Nainggolan's pass, then Diego Perotti put a penalty into the top right corner after Milner handled Nainggolan's shot.
Afterwards, Klopp declared: "Long term perfect performance for pretty much 80 minutes or so. We made defensively one mistake.Penalty is not a penalty but that is the situation and now it is 5-2. Of course we would have been more happy with 5-0 or 5-1 but 5-2 is a fantastic result. We go there and try again.
"We had all these runs behind, it changed the game completely and they couldn't cope with that. We scored these goals and could have scored more. That is all positive, at this moment it doesn't feel all positive because they scored these two goals but tomorrow I will see the really good part of the game.
"It is absolutely better than I thought before the game but at the moment of course a a little mistake."
Klopp admits an injury to Alex Oxlade-Chamberlain is a concern.
"Oxlade-Chamberlain is probably a really bad injury," Klopp added. "That is bad news for us. The squad doesn't get bigger at the moment so we need to be creative in the next few games."