Jordan Henderson admitted Liverpool "basically gave" Roma two goals, but urged his teammates to look on the bright side after Tuesday's 5-2 Champions League win over the Serie A side at Anfield.
Two goals and two assists from Mohammed Salah had guided Liverpool to a 5-0 lead in the semifinal first leg, but a strike from Edin Dzeko and Diego Perotti's penalty gave Roma hope ahead of the return game in Italy.
"We'll obviously be disappointed in the two goals because It felt as though we were in full control but we basically gave them two goals -- you can't really do that in the Champions League," Henderson told BT Sport after the game.
"But at the same time we played well, we've won the game, and we'll go there with a three-goal advantage."
Roma were able to overturn a three-goal deficit in the previous round against Barcelona, and Henderson said reaching the final would not be a foregone conclusion.
"It will be difficult as you've seen in the last round they came back against Barcelona, one of the best teams in the world, and they managed to knock them out," he said. "So it'll be a really tough challenge for us. ...
"Overall we have got to stay positive -- another huge game. We knew it would not be easy tonight, we know it will not be easy there. It will be really tough as Barcelona found. So we need to be on our best and go there and score there as well with the forward players we've got.
"It will be a challenge, but one we've got it look forward to and hopefully can finish the job off."
Liverpool defender Virgil van Dijk also said he was frustrated to let Roma back in the tie.
"I think it was a fantastic evening, five good goals, a lot of passion, a lot of good play at times against a very good Roma. But to concede two goals in the last 15 minutes, that stays in my mind," Van Dijk said.
"Right now it's obviously a good result to take with us to Rome but to concede two like that is frustrating."
Roma defender Federico Fazio pointed to the comeback against Barcelona as inspiration for the second leg.
"We scored the two away goals, but also had plenty of chances in the first half. We have to keep going," he told Mediaset Premium.
"We are players, we are athletes, we'll fight to the last second. It's not lost yet. We worked so hard to get here and, with our people behind us, we'll try to turn it around to the very last moment of the tie.
"We fought the whole game, this is football, we'll fight again in the second. Let's not forget the story of how we got here."