The Arsenal midfielder is struggling with an Achilles tendon injury ahead of his side's quarter-final encounter, and will start the match from the bench
The Arsenal midfielder missed the Czechs' last Group A game due to an Achilles tendon problem, and went to see a specialist in Prague earlier this week to undergo treatment.
Nevertheless, team manager Vladimir Smicer has now revealed that the attacking midfielder isn't fit enough to start versus Portugal.
"Rosicky is not going to be in the starting line-up, but will be ready to come to play from the bench if it is necessary," Smicer stated on Czech television.
The absence of Rosicky means that Daniel Kolar is likely to get the nod again in midfield in Thursday's encounter. The match is scheduled to kick off at 20:45CET.