Head coach Matt Sherratt has confirmed Cardiff have lodged a complaint with the URC against the Lions following the injury to scrum-half Gonzalo Beltranow.
The Argentina international was forced off the field in the first 20 minutes of a match against URC at Ellis Park last week and has undergone surgery for what Sherratt described as a “terrible injury”.
Bertranou's absence means fly-half Tinus de Beer will act as cover scrum-half for Ellis Bevan in Wales' match against the Sharks this week.
The Cardiff manager believed the injury was caused by a deliberate blow to the face by a Lions tackler and said the club had lodged a complaint with the URC.
Gonzalo Beltranow injury
However, the URC told officials there was no “obvious” mistake.
Asked about the scrum-half's availability, Sherratt said: “He has either a fracture in his eye socket or a fracture in his cheekbone.”
“I don't usually say things like this, but I wasn't very happy with the actions that caused the injury.
“It looked like he was waving his arms.” [and] We have dealt with it through appropriate channels.
“It never became clear, but I felt sorry for him because it was a bad injury.”
He added: “It's a bad injury. It might not be for long. Cam Wynnett had something similar to Antoine Dupont at the World Cup, so hopefully he can do something in our season.” He can play a role. Gonzalo is scheduled to undergo surgery today, so I hope it goes well.”
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Bertranou suffered facial fractures in the accident and was initially taken off the field to undergo an HIA, but did not return.
Cardiff lost against the Lions, and the hosts' second-half haste saw them concede two crosses, resulting in a 34-13 bonus point victory and keeping their slim hopes of making the play-offs alive.
This week, they face the Sharks with both teams out of the URC knockout stage.
Cardiff are expected to send many of their frontline players to London ahead of schedule for the Challenge Cup final against Gloucester, and it is possible that Cardiff could outperform the Sharks in terms of overall results.
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