Wales' record cap holder Gethin Jenkins will have an X-ray on a facial injury after coming off as a replacement in Cardiff Blues 22-17 win over Dragons.
Wales wing Hallam Amos also limped off for the hosts and is set to miss their home match against the Ospreys on Sunday, 31 December.
Jenkins, 37, and with 129 Wales caps, was injured in a tackle in his first match since mid November.
"He had a nasty bang to the face," said Cardiff Blues head coach Danny Wilson.
"He will have an X-ray to check there is nothing broken but he is quite confident there is not.
"It is just a case now of concussion protocols he will have to go through."
It was the prop's third game of the season following knee and calf injuries.
He is now set to miss the 31 December match against the Scarlets at the Arms Park after suffering the blow while attempting to tackle back-rower James Sheekey.
"I feel for him at the moment because he is not having a huge amount of luck," said Wilson.
"There is nobody who works harder to get on the rugby field.
"Hopefully it is a minor thing and we can get him back in the next couple of games."
The match also saw Amos limp off with what looked like an ankle injury.
"I don't know exactly what the extent of the injury was but he wasn't able to play on," said Dragons coach Bernard Jackman.
"I doubt whether he will be fit to face the Ospreys (on 31 December)."