The Brazil international made his comeback at the weekend after three months out with a thigh problem, having already been sidelined since last November after knee surgery. It provided the Reds with defensive surety in the middle of the pitch and allowed their full-backs and more creative midfielders, Allen and Steven Gerrard, to get forward. The 1-0 victory over Southampton, which included a completely one-sided first half, lifted Liverpool to within seven points of third-placed Chelsea. And Allen thinks the return of Lucas can help them close the gap further.
"You're always going to miss quality players like Lucas and it's great to have him back in the side," said the Wales international.
"His return, with the steel and quality he brings, is only going to help the team going forward.
"It's a very important role. If you look at the top teams, they all utilise that position and have a quality player there and it is for a reason, it is vital for the way we want to play.
"With him back playing, I'm sure we'll get the benefits of that in terms of points and our position in the table.
"We've closed the gap (to the top four) a bit and for a club like Liverpool, that has to be our target.
"We have got a run of games now where we want to pick up points and further reduce that deficit."
Allen is also hopeful the freedom playing alongside Lucas brings will allow him to show a different side to his game as on Saturday he was released to attack more having spent most of his debut season at Anfield in the holding role.
"That's more my natural position," he added.
"I haven't played there for a while so I found myself trying to get back into the swing of things.
"I had that security of knowing that Lucas was there.
"It gives you the chance to express yourself further up the pitch, and try to get involved in creating and scoring goals."