Denmark midfielder Niki Zimling (extreme right in the picture) left the team's training session in an ambulance with an unknown injury on Friday, just a day before its opening game at the European Championship.
Denmark was just finishing the session on the eve of its Group B match against the Netherlands when Zimling was carried out of the stadium in Kharkiv on a stretcher. His right boot had been taken off as he was lifted into the ambulance.
It wasn't immediately clear what kind of injury he had received.
Zimling, 27, who plays club football for Brugge in Belgium, is a regular starter in Denmark's lineup as a defensive midfielder alongside William Kvist.
If he cannot play against the Netherlands, he could be replaced by 32-year-old Christian Poulsen, one of the most experienced players in the squad.
Before the incident at Metalist Stadium in Kharkiv, Denmark coach Morten Olsen had praised the form and fitness of his 23-man squad. He was particularly impressed with striker Nicklas Bendtner, who was hit by injuries in the run-up to the 2010 World Cup.
Bendtner, who played on loan for Sunderland last season after failing to make regular starts for Arsenal, has said he is entering Euro 2012 in great shape.
"He has had a very good training camp," Olsen said of Bendtner on Friday. "Physically he is 100 percent."
Olsen said the Netherlands - led by big stars such as Robin van Persie and Arjen Robben - will be the clear favorite Saturday.
"They have a lot of qualities and you can't get around that," Olsen said.