"It doesn't look too good for Tommy at the moment. It looks as though he has broken a bone in his hand and he probably needs an operation. I would say he will be going home," head coach Warren Gatland announced at the post match press conference.
"The experience he brings, and being able to play right wing, left wing, centre and full back, means he is a huge loss for us. He slotted in well on the left wing tonight.
"If you think about the two guys we are bringing out in terms of replacements they are absolutely quality players. If Alex Corbisiero hadn't been injured then he would have been in the mix and Ryan Grant has had an excellent season as well.
"Speaking to the Scottish players they say he will come here, work hard and he is good. I really feel for Cian and Gethin, but we've got some real quality coming in and, if we get a replacement for Tommy, he will be a quality player as well."
England and Leicester Tigers centre Manu Tuilagi was another casualty on the night, but Gatland said his shoulder injury was no cause for concern.
"Manu is fine. He just got a bit of a stinger in his shoulder and had a bit of a dead arm. He said he had lost a bit of feeling, but it was coming back after the game," said Gatland.