Wales captain Sam Warburton faces a sleepless night after suffering a knee injury in the Six Nations win over France on Saturday.
The British and Irish Lion was forced off late in the second half of the 20-13 victory in Paris, a result that keeps up Wales' challenge for the title ahead of a crunch meeting next up with Ireland.
Dan Biggar's 60th-minute try and five penalties from the boot of Leigh Halfpenny guided the visitors to the win, but afterwards all attention was on Warburton's fitness.
"My knee just swelled up and I couldn't run at full pelt," said Warburton, who was already wearing strapping and an ice pack on his right knee at the final whistle. "It is just a bit of swelling. I will be up every two hours tonight icing it, and [will] reassess tomorrow morning."
Wales head coach Warren Gatland added: "With Sam's knee, we are not too sure how serious that is.
"He won't be going to the [team] dinner tonight, he is going back to the hotel and we are just hoping it is not too serious.
"He has just taken a knock on the knee, and it is probably just waiting for 12 hours or so."
