Real Madrid forward Gareth Bale will miss Wales' World Cup qualifiers against Georgia and the Republic of Ireland with a calf strain.
They are really important matches as Wales are trying to get into second place in their group.
That would earn them a two-game play-off match which, if they won, could get them to their first World Cup since 1958.
Bale, who's scored four goals so far in this qualifying campaign, joined the Wales squad on Monday and, despite sitting out training, it had been hoped he would be fit.
But the 28-year-old's injury means he will not travel to Georgia.
Wales haven't won a match without the Real Madrid forward since 2013, drawing three and losing three matches when he's not playing.
Barnsley striker Tom Bradshaw has been called up to the Wales squad in his place.