"The national team captain, who trained at the gym yesterday (Wednesday), has an infection in his right foot and is being treated with antibiotics," the Portuguese Football Association writes on its website.
The Juventus striker is not Portugal's only injury concern.
Lille's midfielder Renato Sanches will definitely miss the two internationals due to an unspecified injury.
Portugal, who won the first edition of the Nations League last year, start the tournament at home against Croatia on Saturday and then fly to Stockholm for a match against Sweden at Friends arena on Tuesday.
CLIP: Kulusevski on the meeting with Ronaldo: "Not as I thought" (August 9, 2020)
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Dejan Kulusevski will be teammate with superstar Cristiano Ronaldo next season.
But they have already met on the pitch.
Photo: SVT / Bildbyrån