Gerard Houllier hailed Liverpool's brilliant performance to beat Roma 2-0 in the fourth round of the Uefa Cup.
Michael Owen scored both goals as the Serie A leaders were sent crashing to their first home defeat of the season.
But Houllier warned of the dangers of getting carried away by the win at the Stadio Olimpico.
He said: "There's still the second leg. Roma are an outstanding side, a great team but we managed to keep them quiet and nullified them.
"But the second game will be very difficult.
"They are a good team who are difficult to beat, nobody has won in this stadium this season, so that highlights our performance.
"We limited them to one chance in the first half, and after Michael Owen scored so early in the second, it changed the game. From then on we showed confidence and the defending was absolutely brilliant. We were so disciplined.
"And we showed the composure needed to win at the highest level. I must admit I was worried with us having four players coming straight back from injury, particularly with the quality of opposition.
"But this result is a step forward to what we want to achieve. If we had lost we would have been compared with the great Liverpool teams of the past, but that is not fair because we are still in a building process."
Houllier was also delighted with Owen's display, saying: "Michael was tremendous, he looked very sharp and I'm very pleased for him. Robbie (Fowler) worked extremely hard, very unselfishly and played a real captain's role."
Roma coach Fabio Cappello said: "We gave Liverpool a gift for the first goal. I just hope they do the same gift for us in the second match!
"We found it very difficult to attack, they defended so well, packed their box and marked us very tightly.
"I would have wanted Batistuta on earlier, but he finds it hard to play three games in eight days. In the circumstances this was the best side I could put out."