A 12-game unbeaten run had appeared the perfect response to early-season criticism of Emery at PSG, but in the last week the Spaniard has seen his side humbled 3-0 by Montpellier and then left to scramble a 2-2 draw with Ludogorets in the Champions League.
After two such worrying performances, it is debatable whether Emery could even survive a defeat at home to Nice, which would leave the defending champions seven points adrift of the southern upstarts with the season's halfway stage approaching.
"It is a difficult spell, but we will show a reaction on Sunday in what is a huge match for us," insisted midfielder Blaise Matuidi, just about the only PSG player deserving of pass marks against Ludogorets.
PSG needed a late Angel di Maria equaliser to avoid defeat at home to the Bulgarians after a lacklustre display but the result meant they finished second in Champions League Group A to Arsenal.
"This disappointment must give us the desire to lift our hands and show a different face in the last 16. We must improve, and that starts on Sunday against Nice," said Emery in his still stumbling French.
PSG have Adrien Rabiot and Javier Pastore on the sidelines while Di Maria is in wretched form, so they may look to Hatem Ben Arfa for creative inspiration against the club for whom he starred last season.
Without him, the side from the Cote d'Azur -- with a reported budget less than a tenth of PSG's -- have gone from strength to strength this season under Lucien Favre and they have topped the table since mid-September.
They have only lost once in the league all season and impressed in beating Toulouse 3-0 last weekend to hold a three-point lead over Monaco and a four-point advantage over the capital giants.
Mario Balotelli is in line to feature after making his comeback from a month on the sidelines with a calf injury in Thursday's Europa League meeting with Russian outfit Krasnodar.
Monaco travel to Bordeaux on Saturday knowing a win would take them provisionally top of the table, above Nice on goal difference.
Leonardo Jardim's prolific side are still running at an average of more than three goals per game and were able to rest key players for Wednesday's Champions League defeat to Bayer Leverkusen in Germany having already qualified for the last 16 as group winners.
They are targeting the symbolic title of topping the table at the year's end and striker Valere Germain said: "It would be nice to be autumn champions and we will give everything in the final matches of the year to do that."
Lyon will aim to bounce back from the disappointment of being eliminated from the Champions League after failing to get the better of Sevilla as they host Rennes.
Rennes are fourth but have struggled away from home this season and Lyon can leapfrog them with a win.
Bruno Genesio's men also have a game in hand after their match at Metz last weekend was abandoned when firecrackers were thrown at OL goalkeeper Anthony Lopes, leaving him with "acoustic trauma" but no lasting damage.
Nantes, who are in the relegation zone, will have new coach Sergio Conceicao watching from the stands when they host Caen on Saturday.
Conceicao, the 42-year-old former Portugal winger, was in charge of Vitoria Guimaraes last season.
Fixtures (kick-offs 1900 GMT unless stated)
Dijon v Marseille (1945 GMT)
Bordeaux v Monaco (1600 GMT), Bastia v Metz, Lille v Montpellier, Nancy v Angers, Nantes v Caen, Toulouse v Lorient
Lyon v Rennes (1400 GMT), Saint-Etienne v Guingamp (1600 GMT), Paris Saint-Germain v Nice (1945 GMT)