Northern Ireland are awaiting scan results following the groin injury picked up by key forward Kyle Lafferty in training on Tuesday.
After Tuesday’s session, boss Michael O’Neill said he had “no concerns” about Lafferty’s fitness for Sunday’s Euro 2016 opener against Poland.
However, Lafferty, 28, was unable to take part in Wednesday’s training.
As his team-mates trained Saint-Georges-de-Reneins, Lafferty did a workout on an exercise bike.
Norwich striker Lafferty pulled up in Tuesday morning’s training session after appearing to stretch his groin, but O’Neill said it was “just a little twist”.
“It was precautionary to take him out of training. We’re just being careful,” added the Northern Ireland on Tuesday.
“After examination by the doctor, he feels good. We’re more concerned about the thunder and lightning, to be honest.”
Lafferty was the only member of the Northern Ireland squad to miss training on Wednesday morning as Craig Cathcart and Gareth McAuley took part in the session after not being involved on Tuesday.
The Norwich striker’s seven goals were crucial to Northern Ireland’s surprise qualification for the finals in France.
The county Fermanagh man appeared to be in some pain after reaching to control a ball during Tuesday’s session.
He was directed into an ice bath on the side of the pitch at Northern Ireland’s training base at Saint-Georges-de-Reneins near Lyon, and afterwards walked gingerly to the changing rooms.