Montpellier - Springbok wing Cheslin Kolbe, who played a major role in the Springboks' World Cup triumph, suffered a rib injury in Toulouse's European Champions Cup win against Montpellier on Saturday.
"He has hurt his ribs and he is going to have it for a little while," said Toulouse coach Ugo Mola after the game.
Kolbe, who was making his first start for Toulouse since returning to action after the World Cup, was injured in the 61st minute when he was tackled by 130kg Fijian winger Nemani Nadolo.
Kolbe will undergo tests in the next few days to determine the nature of his injury and the length of his absence.
Montpellier also suffered an injury in the match, which Toulouse won 26-18, with former France No 8 Louis Picamoles stretchered off after just three minutes.
The 33-year-old, who retired from international duty after the World Cup, was initially diagnosed with a torn cruciate ligament in the left knee. He will undergo an MRI on Monday.
"This is not a good sign but we will wait for the results," said Montpellier coach Xavier Garbajosa.