The hosts were on a dire run of games coming into this fixture, winning just once in their last six games, while PSG were looking to extend their unbeaten run to nine games and jump to the top of the Ligue 1 standings.
Lorient took a shock lead in the 36th minute after midfielder Laurent Abergel pounced on some poor defending from the PSG defence before firing a shot past shot-stopper Sergio Rico.
PSG drew level on the stroke of half-time when Neymar was hacked down in the penalty box. The Brazilian superstar stepped up and calmly slotted home his spot-kick to end the first half.
Neymar put the visitors ahead 13 minutes into the second half after he was awarded another penalty after being fouled in the 18-yard box. That was the 28-year-old's sixth goal in ten outings for PSG this season.
However, relegation-threatened Lorient stormed back to level terms, thanks to But Yoane Wissa in the 80th minute.
The 24-year-old, who came off the bench for Armand Lauriente, played a brilliant one-two to get past the PSG defence before Thilo Kehrer's deflected block fell calmly for him to smash into the net.
With PSG pouring forward in attack searching for a winner, substitute Terem Moffi cleared the ball before finishing an excellent run with a goal to spark wild celebration among the Lorient players.
Lorient have now picked up back-to-back wins for the first time this season while Mauricio Pochettino’s men missed out on a chance to leapfrog Lyon at the top of the Ligue 1 table and into first place.
On that note, let us have a look at the PGSG player ratings.
Sergio Rico 5/10
The PSG goalkeeper Sergio Rico was let down by his shambolic defenders, as he was helpless in all three goals.
Alessandro Florenzi 5.5/10
The former AS Roma full-back Alessandro Florenzi had a quiet night, as he failed to make any difference in the PSG defence. He linked up well with Angel Di Maria on the right flank and sent in a few decent crosses; however, he faded as the game progressed.
Thilo Kehrer 5.5/10
The former Schalke man Thilo Kehrer put in a decent performance for the Ligue 1 champions. Despite PSG conceding three goals, he was arguably the standout player in the back line.
After the PSG defence was split open by Yoane Wissa's one-two, Kehrer made an attempt to block the 24-year-old's shot, but his sliding tackle only fell calmly for the striker to tuck home.
Presnel Kimpembe 4/10
It was a performance to forget from the Frenchman Presnel Kimpembe. Laurent Abergel took advantage of his error to open the scoring in the first half. Kimpembe and the entire PSG defence were beaten by a simple one-two for Lorient’s second goal, while he was nowhere to be found for the hosts' third of the night.
Layvin Kurzawa 6/10
Layvin Kurzawa operated brilliantly on the left flank of the attack, as he linked up well with Kylian Mbappe while provided an outlet for PSG.
Angel di Maria 5.5/10
Despite staying on the pitch for much of the game, Angel di Maria was simply anonymous; the Argentine forward had no attempt on goal or created a chance. He won a number for tackles though, but made no meaningful contributions during his 81 minutes on the pitch.
Danilo Pereira 4.5/10
The Portuguese Danilo Pereira got booked in the second minute of the game after a silly challenge on Laurent Abergel.
A shambolic piece of defending from Pereira on the edge of the box gifted Lorient their opener in the 36th minute.
Leonardo Paredes 5.5/10
Leonardo Parades was tenacious in midfield, as he kept play ticking while putting in his usual defensive contributions. He was hooked off in the 81st minute for Idrissa Gueye though.
PSG's best player by a mile, Neymar calmly converted his two spot-kicks to put PSG in front. In a fine display, the Brazilian created one big chance while also finishing with two key passes, but he was unlucky to end up in the losing team.
Kylian Mbappe 5/10
A poor performance from Kylian Mbappe, as he was uncharacteristically quiet the entire game. The Frenchman finished with no shot on target, as he failed to test the Lorient defence.
Mauro Icardi 5.5/10
The Argentine Mauro Icardi won PSG’s second penalty after he was clipped down in the box. He, however, missed a header from point-blank range that could have put PSG 3-1 up after Kurzawa whipped in an excellent cross.
Player ratings of PSG substitutes
Idrissa Gueye 6/10
Despite coming on in the 81st-minute, Idrissa Gueye put in a characteristically solid performance for PSG. He was accurate with his passes, completing 100% of them, while winning one aerial duel.
Pablo Sarabia 4/10
The former Sevilla man Pablo Sarabia came on for the final nine minutes of the game but made no telling contribution.