Reds boss Brendan Rodgers' former side were a shadow of themselves - distracted by Sunday's Capital One Cup final at Wembley - as they were dispatched 5-0 at Anfield. The home side need goals on Thursday to overturn a 2-0 deficit against Zenit St Petersburg in order to reach the last 16 in Europe.
And having suffered back-to-back defeats, including a home loss to West Brom last Monday, Lucas thinks the goal rush provided the perfect antidote to a disappointing few days. "We started the week thinking it could be a really good week for us," said the Brazil midfielder.
He added: "But we had the defeat to West Brom and then the Europa League loss but we have finished the week off in a positive way by scoring five goals and keeping a clean sheet.
"We know we still have to improve a lot but this victory will give us confidence going into Thursday to try to get through against Zenit. With the way we played over there, we created a lot of chances, if we do that again and take them then we'll have a great chance of getting through to the next stage."
Captain Steven Gerrard's 34th-minute penalty provided the crucial breakthrough, succeeding from the same spot from which he had failed against West Brom. Lucas felt they had learned from the chastening Baggies experience, when they dominated but conceded twice in the last nine minutes.
"Unfortunately we couldn't score early but we kept going then towards the end of the first half we got the penalty. The second half we started really brightly and getting the second goal so quickly (after just 16 seconds) was very important and after that we just needed to make sure we controlled the game."
Inconsistency has dogged Liverpool for well over a year, preceding the reign of Rodgers who left Swansea to take over from Kenny Dalglish in the summer.
"It's difficult to explain. As players you get frustrated a lot of times as well," added Lucas. "When you think we are starting to get some good momentum we have a defeat and a setback.
"But there is still time to get that consistency. Our league position is not great (seventh, nine points off the top four having played one match more) but we must keep fighting and see what happens. If we can get that consistency then we can finish this season on a high."
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