The Reds had Steven Gerrard sent off as they slumped to a 2-1 loss to the Red Devils at Anfield in their most recent Premier League outing to dent their hopes of a top-four finish.
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Victory for Arsenal at The Emirates on Saturday lunchtime would leave the Reds nine points behind the north London club as the race for Champions League qualification hots up.
And midfielder Lucas admits that Brendan Rodgers’ men can ill afford to lose to the Gunners ahead of the crunch clash.
Speaking to Liverpool’s website, Lucas said: “Of course losing could open the gap too much but I think we’ve showed this season when we are playing well we can play against any team.
“We remember the semi-finals against Chelsea and I know we ended up losing the game after extra-time, but I think we created a lot of chances to win the game and we should take that into the Emirates against Arsenal.
“We are on a good run and that was our only league defeat in 2015 which gives us confidence to keep going and try to win the game, because it will be important if we want to close the gap for the top four.”
Liverpool are currently fifth in the Premier League table, while Arsenal are third and just a point behind defending champions Manchester City.
The two sides drew 2-2 at Anfield when they last met in the top-flight back in December.
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