Paris Saint-Germain coach Luis Enrique expects his side to be pushed hard over the closing months of the Ligue 1 season, starting with Sunday's visit of unpredictable arch-rivals Marseille.
European champions PSG have won their last six league games but face an unexpected title challenge from a dogged Lens, who are just two points back and reached the French Cup quarterfinals in midweek.
"It's a very hard league," said Luis Enrique after last week's 2-1 victory at Strasbourg, where PSG grabbed a late winner after being reduced to 10 men when Achraf Hakimi was sent off.
"Lens deserve to be up there with us. It will be difficult. Marseille and Lyon are improving as well. It's going to be a tough end to the season."
PSG have had a rare week between games after their surprise exit in the domestic cup but must navigate a two-legged Champions League play-off with Monaco later in February for a place in the round of 16.
Marseille seemed to be heading for the knockouts as well before an improbable turn of events sent them crashing out, provoking a furious reaction from supporters at Tuesday's French Cup tie.
After blowing a two-goal lead in a 2-2 draw at Paris FC last weekend, Marseille dispatched Rennes 3-0 to move on in the cup, but disgruntled supporters unfurled a series of banners to voice their anger at the club's Champions League debacle.
"The fans are smarter and more knowledgeable than people think. They almost always tell the truth," said De Zerbi, after players and club officials met Monday with fan representatives still smarting from the disastrous 3-0 loss at Club Brugge.
"They were disappointed about Brugge, and they're right - it's a match to be ashamed of.
"We have a team that gives you the impression of being very strong, so it's normal that there are expectations. Sometimes they're met, sometimes not."
"It's a strange team, hard to figure out," added De Zerbi. "We're looking for a bit of continuity and consistency."
Marseille beat PSG 1-0 in September and nearly got the better of Luis Enrique's team again in last month's Champions Trophy in Kuwait, losing on penalties after conceding a stoppage-time equaliser in a 2-2 draw.
PSG will be without the suspended Hakimi this weekend while winger Khvicha Kvaratskhelia is an injury doubt, but Ze Derbi knows Marseille will have to be at their best to win.
"PSG are the strongest team in Europe," said De Zerbi. "I'm not saying that just because they won the last Champions League - I really believe it."
PLAYER TO WATCH: Ciro Immobile
Paris FC were busy in the the winter transfer window, both building for the future while trying to ensure they are not dragging into a relegation battle in the second half of the season.
The club has sought to address its shortcomings in attack by signing four-time Serie A top scorer Immobile, who made his debut off the bench in Wednesday's cup defeat by Lorient.
Immobile turns 36 in two weeks and is yet to score this season after an injury-hit spell at Bologna, but Paris FC hope the Euro 2020 winner – with a record of 304 goals in 587 club matches – still has more to give at the top level.
KEY STATS
4 - games in which Marseille have dropped points after conceding goals in second-half stoppage time.
9 - successive home wins in the league for Lens, who have not conceded at Stade Bollaert in their last five matches
12 - Lorient's unbeaten run in all competitions. They beat Paris FC 2-0 to reach the French Cup quarterfinals
FIXTURES (times GMT)
Friday
Metz v Lille (7:45pm)
Saturday
Lens v Rennes (4pm), Brest v Lorient (6pm), Nantes v Lyon (8pm)
Sunday
Nice v Monaco (2pm), Auxerre v Paris FC, Le Havre v Strasbourg, Angers v Toulouse (all 4:15pm), Paris Saint-Germain v Marseille (7:45pm)