The Gunners are currently second in Group B with seven points from four matches, a point behind leaders Schalke.
"When we played them [in France] we were under pressure for periods of the game, and we did well to get a result (a 2-1 win)," Ramsey told Arsenal's official website.
"They have competed against every team [in the group] and shown that they can create and can be a threat, so they will be no pushover. They will want to prove something as well. We have to be aware of that, and be on top of our game on the day.
"The group is pretty tight, so I think you can say we have to win that game. We are at home, so hopefully we can do that and put ourselves in a strong position to qualify."
French champions Montpellier are at the bottom of Group B with just one point from four matches.