The Argentina international picked up a knock in Tuesday's 4-0 UEFA Champions League triumph over Marseille.
However, he insists that the problem is only minor, and is confident of featuring against Sir Alex Ferguson's side.
"I got a kick but I think it's nothing and I should be okay to face Manchester United," he said.
Mascherano also warned United that the midweek victory over Marseille has filled The Reds with plenty of confidence.
"We're close to the top so we need to win on Sunday to get even closer plus it's very important for our fans that we get a victory," he told Uefa's website.
"Liverpool against United is a massive game, maybe the biggest there is in England, so we have to start preparing for it.
"We know we can get a victory and our confidence is obviously high as well.
"When you win 4-0 away it's very good for the team and now we need a repeat of this performance on Sunday."
Glad to see Masch will be fit for the game, as it looked a bad injury at the time, and maybe Sami should have been sent off for that tackle
