Will Grigg has been ruled out of Northern Ireland's European Qualifiers against Estonia and Belarus through injury.
The 27-year-old striker, capped 13 times, has returned to Sunderland for treatment.
Grigg had been recalled to Michael O'Neill's squad after also missing the last three games of last year through injury.
His absence leaves O'Neill with Kyle Lafferty, Liam Boyce, Josh Magennis, Conor Washington and 21-year-old Paul Smyth as options in attack.
Blackburn midfielder Corry Evans also missed training on Wednesday morning and remains a doubt for Thursday's Sky Live match against Estonia with a hamstring problem.
Northern Ireland open their qualifying campaign against Estonia before playing Belarus on Sunday, with both matches at Windsor Park.