Getty Images

Paris Saint-Germain's difficult return to domestic action continued with a 3-1 defeat away at RC Lens on Sunday. After a dramatic late 2-1 win over RC Strasbourg Alsace last Wednesday, Ligue 1's second-placed side gave Christophe Galtier's men an overdue wake-up call.

With no Neymar at Stade Bollaert Delelis through suspension, Kylian Mbappe and his teammates found it tough going and were exposed by a hungry Sang et Or side hot on their heels. Przemyslaw Frankowski put Lens ahead inside of five minutes only for Hugo Ekitike to controversially level before 10 minutes were even on the clock despite a VAR check for a foul on home goalkeeper Brice Samba.

Lois Openda restored the lead for Franck Haise's men just before the half-hour mark with veteran defender Sergio Ramos embarrassed by the lightning-quick Belgium international. Alexis Claude Maurice quickly stretched the home lead three minutes into the second half after a brilliant bit of play from Openda to tee him up.

More than just the goals, though, PSG's second consecutive sluggish display will have concerned Galtier who saw his team bailed out by a debatable late penalty against Strasbourg. The French champions could have been more than 2-1 down at halftime given how well Lens played with captain Seko Fofana particularly impressive.

CBS Sports has the daily soccer podcast for you, covering everything you need to know about the beautiful game. Make sure to give House of Champions a follow for coverage of the biggest games, stories, transfer news with Fabrizio Romano, and everything else going on in the world's most popular sport.

"I struggled to recognize my team," Galtier said after the match. "We lacked cohesion and we fell apart as the game wore on which opened up spaces. It was the opposite of what we should have done. We were technically wasteful and Lens really pressed us. We were also beaten in an athletic sense."

"Lens played really well and deserved to win," added Vitinha. "We wanted to remain unbeaten, but we failed. We will remember this game and try to improve upon it. It is hard to explain what happened, but the first goal and the atmosphere perhaps got to us. Lens understood the game better and performed better."

With 2023 just getting underway, PSG have a lot of work to do over the next month or so if they are to be ready to face Bayern Munich in the UEFA Champions League round of 16. Lionel Messi will be returning to Paris this week after Argentina's FIFA World Cup success in Qatar and Galtier needs to get his star-studded team back into their pre-tournament break rhythm.

The likes of Mbappe are expected to get some rest in the Coupe de France this coming week with third-tier Chateauroux away on Friday. Messi should make his return in that one before PSG return to full strength the following midweek in Ligue 1 against Angers SCO and it is at that point that Galtier really needs his players to knuckle down.

"Neymar and Leo are two great players who make a big difference and create chances," Marquinhos said. "It is not an excuse, though -- we lacked cohesion, efficiency, and intensity. That is what cost us here."

Before the World Cup, Les Parisiens rode their luck a few times to remain unbeaten as they quite easily could have gone down to the likes of SL Benfica in the Champions League when both finished as draws. Stade de Reims also held PSG in that wobbly period so this is not even the first blip in form this campaign.

Scoring goals has not been that much of an issue given that they have already scored upwards of 60 times across all competitions. However, keeping them out is a major worry now with captain Marquinhos' form suffering, Ramos indispensable because of Presnel Kimpembe's injury and precious little depth available to Galtier.

To make such a result all about PSG would be disrespectful to Lens, though. Haise's men have been punching above their weight all season to now sit four points behind the capital club which could have been even less had midweek results gone differently.

There are quality elements in this Sang et Or side such as Fofana, Openda, Samba, and Facundo Medina, but what is aiding their current success is Haise's ability to get the absolute maximum out of them. Well organized on and off the pitch with a clear identity is bringing a Champions League return closer to reality for the Northerners.

We are not yet at the halfway point of the season but Lens are absolutely in this Ligue 1 title race and it is reaching the point where failure to qualify for Europe in one form or another is fairly unthinkable. If Haise can keep them on track, PSG cannot afford to slip up many more times before the end of the campaign.