In-form PSG have won eight successive league matches but they could be three points off top spot when they arrive at a sold-out Allianz Riviera, if Monaco beat Toulouse on Saturday.
Third-placed Nice have made their home ground a fortress this season, winning 13 and drawing four in front of their own supporters to leave themselves six points behind the top two ahead of the weekend fixtures.
PSG boss Emery knows his side will have to be at their best to secure three points on the south coast on Sunday evening.
"Tomorrow will be a great game, against a team that has shown great things and has a great season," he told PSG's official website.
"We are six points ahead of Nice but they are unbeaten at home and have lost only two matches in 2017.
"For us it is a big challenge, facing a motivated team who will want to beat us.
"But all my players are ready, they are aware of the importance of this meeting and we will want to give everything on the pitch."
The Parisians booked their place in the final of the Coupe de France in midweek, thrashing a much-changed Monaco side 5-0 at the Parc des Princes.
Emery's men face a much more difficult task to overcome the principality club in the title race but, at this stage, the Spaniard insists he is only focusing on his own club.
"We need victory tomorrow," he added.
"Winning the championship is our goal, Monaco is in front but we think only of ourselves, we only think to win all the matches we have to dispute.
"I am optimistic, especially when I see the work provided by my players."
Read the full article on eurosport.co.uk: Unai Emery urges Paris St Germain to end Nice's impressive home record