Bordeaux striker Samuel Callo fell on the pitch in a French Ligue 1 game in Marseille on Sunday, where temperatures rose to 30 degrees.
The 23-year-old Nigerian international fainted and slipped to the level of the stadium velodrome in the early stages of the match.
Distraught teammates gathered around the victim Kalu and waved in front of the bench to seek medical help.
After a few heartbreaking moments, Kalu managed to stand up but was replaced by Remy Odin.
The incident happened just two months after Denmark’s Christian Eriksen suffered a heart attack in the Euro 2020 match.
“The Kalu incident made us feel cold. It’s always a bit shocking for the spectators and the players on the pitch,” said Odin, who managed to score in a 2-2 draw.
“With what happened to Ericsson in the euro, we think about it.
“According to doctors, this is a simple ailment but it will definitely be tested on Monday.”
In June 2019, Kalu was hospitalized after experiencing dehydration while training with Nigeria in the Egyptian heat during the Africa Cup of Nations.
“I was thinking about what happened during the euro,” admitted Bordeaux coach Vladimir Petkovic.
“With the medical team, we chose to replace him so that no risk is taken. In these cases, football takes the back seat.”