The 23-year-old fell to the ground in the sixth minute when Dimitri Payet was preparing to take a free kick in the middle of searing temperatures at the Stade Velodrome.
After rushing to the winger and providing a human shield around Kalu, players from both teams immediately called for the attention of the medical team.
With the help of his teammates, some holding an ice pack against his head, the Nigerian was able to get up and walked off the pitch.
Having resumed play for some minutes, Kalu was replaced by Remi Oudin in the 14th minute as the match ended in a 2-2 draw.
The cause of the incident is yet to be known as it is not the first time Kalu has collapsed on a football pitch.
The former Gent forward collapsed in Nigerian team's training session during the African Cup of Nations back in 2019.
Kalu received a standing ovation from the fans for his brave attempts to play on following his collapse.
The pacey winger's situation brought back memories of Eriksen's collapse during the Euro 2020.
The Danish midfielder's life was saved through the administering of CPR on the pitch and his heart was re-started with a defibrillator before he was taken to hospital, where he recovered having undergone a heart surgery.
Bordeaux will look to return to winning ways when they host Angers in their next game on August 22.
