The Belgian has urged his team-mates to guard against complacency in the FA Cup and insists that the Reds will be taking the competition seriously
The seven-time winners were unceremoniously dumped out of the competition in the fourth round at Boundary Park last January, losing 3-2 to the League One side.
And goalkeeper Mignolet, who joined from Sunderland in June, has called for focus as the Reds look to secure a safe passage into the draw for round four.
"For them it is already a cup final," Mignolet told the Liverpool Echo.
"It is already a big game for them to look forward to and they will come here and try to show everyone what they can do at a ground like Anfield. We have to make sure we are professional and do a job."
The Belgium international added: "We want to win any game. That doesn't make any difference whether it is the FA Cup, Capital One Cup or any other games - we try to step on and prepare ourselves and make sure we get out of the game what we can get out of it.
"I would always watch the FA Cup finals growing up in Belgium. It is a very important competition. It is a big opportunity as you can play at Wembley but that is far ahead of us.
"The next game is the most important one and before you get to that stage you have to win a lot of games and against Oldham it won't be an easy game."