Toulouse are already guaranteed a place in the semi-finals while Montpellier are also guaranteed a top-six spot.
And Dusautoir, who captained France in every game of the RBS 6 Nations this year, insists his side cannot afford to look ahead to the semi-finals having lost three of their last five games in the league.
He said: "If we play at our best, there is a good chance we'll win. If not it could be very tough.
"We are concentrating on the preparation for the semi-finals but we'll have another two or three weeks after to get ready for the semi.
"Since Montpellier have reached this level you can't say they are here to spoil the party. They are where they deserve to be. They are a potential French champion, we need to treat them as they deserve. We respect them.
"Their coach has made them aware of their strengths. In recent years they have recruited well. With the quality players they already had it's the sign of a top club.
"We're getting ready to welcome a top quality team."