The 32-year-old has been delighted to see his midfield team-mate return during the Reds' pre-season tour of the United States, citing his knee problem as a serious blow in 2011-12Liverpool midfielder Steven Gerrard believes Lucas Leiva's season-ending knee injury was a significant factor in the Reds' disappointing 2011-12 campaign.
The 25-year-old began to hit form just before damaging his left knee in December, leaving Kenny Dalglish one option short in the middle of the field for the rest of the season.
The Brazil international made his comeback against Toronto FC and again played a part from the bench against Tottenham in Baltimore.
"It [Lucas' injury] was a big factor [on our season], because when he got the injury he was probably our best player, form-wise," Gerrard told the Liverpool's official website.
"He was playing superbly well, and he plays that position in the team where he does the ugly work, the work you don't really like to do: breaking up the play, protecting the back four, and when we lose the ball and teams counter-attack, he stops a lot of goals.
"It's great to have him back. He's a great person; he's great for the squad."
Originally signed by Rafael Benitez in 2007, Lucas' form was criticised early on during his Premier League career but he soon turned into a key cog in the Reds' line-up.
Gerrard has explained that the player's physical progression has helped him adjust to the English game and insisted that the rest of the team's squad never doubted his potential.
"You've got to come through the lows and it was certainly a low for Lucas when the fans weren't giving him the backing," Gerrard admitted.
"All the players stuck with him because you could see it in training and in parts of his game that he was a young lad who was always going to come good.
"Credit to him - he rolled his sleeves up, he worked hard, he hit the gym and got himself stronger physically and it's turned around for him."