Yulia Tikaeva, 20, is in intensive care with “serious head injuries” after she clipped the edge of the safety net then crashed onto the ground below.
Children and their parents watched in horror as the Muscovite artist fell head-first the equivalent of four storeys, landing on a hard floor during the acrobatic performance in Gomel.
She was unconscious when she was carried away on a stretcher after the 40ft fall.
She has major swelling on her head but doctors say “no bones are broken”.
The performer is under close medical observation after the accident on Friday.
A spokesman for Gomel city circus said: “Yulia is still receiving medical treatment.
“Her skeleton is intact, there are no no fractures.
“She has a head haematoma but doctors say that so far surgery is not needed.
“Time will go and we’ll see how she feels.
“All of us are thinking about her.
“Many thanks once again for being worried about her.”
Another source said her head injuries were “serious”.
A spectator called Elena said: “She was not caught in time she fell behind the safety net, with her face down.
“We had seats in the sixth row and saw how she was down…
‘The crowd applauded when she was carried away on a stretcher.
“Circus workers say that by the end of the show that night they received a call from hospital that the girl was alive but still unconscious.”
Another member of the audience Margarita said Yulia “was flying from the hands of one male artist to another.
“She only touched his hands and fell …
“It looked like she would fall on the net but she only touched it and crashed onto the floor below.
“All the spectators gasped. She was lying there and did not move. People ran up to her…
“One acrobat showed with his arms that it was the end of performance.
“Then lights went completely off and the girl was carried away. The show went on and horse riders came to perform.
“They wanted to cheer us up after the accident and performed really well.”