The N.10, already affected in this right ankle during the last World Cup, left the Parc des Princes field in the 51st minute.
He scored in the first half.
PSG, beaten 1-0 by Bayern on Tuesday in the first leg, faces the Germans on March 8 in Bavaria for the return leg.
The right ankle of "Ney" turned sharply on a disputed ball to Benjamin André.
Around him on the pitch, his teammates immediately called for the trainers with worried gestures.
On the ground in tears, the Brazilian tried to get up and walk before clapping his hands in rage and lying down in the stretcher.
He walked out with his head in his hands.
The Brazilian Neymar goes out on a stretcher after being hit in the right ankle, February 19, 2023 at the Parc des Princes © Anne-Christine POUJOULAT / AFP
"It's a sprained right ankle, he is having tests to find out the severity of the injury," explained his coach Christophe Galtier.
"It's not bad luck, there are always reasons: the calendar, the sequence of matches... It complicates things, you have to bend your back, but a bent back with a victory is more pleasant".
This injury brings back bad memories for PSG, which has already been deprived of Neymar in the past for high-stakes matches in C1.
He had injured his foot before a round of 16 return against Real Madrid in 2018, and Paris had been eliminated (3-1/2-1).
In 2019, "Ney" relapsed against Strasbourg (2-0) and missed the 1/8 against Manchester United (2-0/1-3) and Paris was still eliminated.
And in 2021, Neymar is injured again, this time in the left adductor, and misses the reunion with his former club, FC Barcelona, still in 8th.
But this time PSG qualified (4-1/1-1), including a hat-trick from Kylian Mbappé at Camp Nou.
Left-back Nuno Mendes also came out early (31st) replaced by Juan Bernat.
For the Portuguese, it is "a stretching of the internal lateral (ligament), it does not seem too serious to me", explained Galtier.
© 2023 AFP