Wales are sweating on the availability of captain Ashley Williams after he injured his shoulder during the 1-0 win over Northern Ireland.
Williams was in great discomfort after clashing with team-mate Jonny Williams in the latter stages of the game, which was won by a 75th-minute own goal from Gareth McAuley.
The Swansea centre-half played the last 10 minutes with his left arm almost completely motionless and a picture of the team celebrating in the dressing room showed Williams wearing a sling.
Chris Coleman had substitute James Collins ready to come on, but Williams played through the pain barrier and Coleman hopes to have him available for their quarter-final against either Belgium or Hungary on Friday in Lille.
"He's a bit tender with his shoulder and the next 24 or 48 hours will be crucial," Coleman said.
"We have to see whether it's bruising, just an impact, or whether - hopefully not - there's damage to any ligaments or a tear in the muscle.
"I thought he was struggling because he couldn't move his arm. There were only a few minutes left and I was going to take him off.
"We had James Collins there ready, but Ash said he was okay to continue and I trust my captain.
"We we were right to keep him on the pitch because he still made some important interceptions and his presence for us is huge."