Luka Modric escaped significant injury in Croatia's 1-1 Euro 2020 qualifying draw with Wales, with Real Madrid confirming he suffered bruising to his right quadriceps.
The midfielder had to be helped from the pitch by Croatia's medical staff with a minute of normal time remaining, having received a knock when he fouled Harry Wilson and earned a booking in Cardiff on Sunday.
He underwent tests after returning to his club, with the results announced on Tuesday.
"Following the tests carried out today on our player Luka Modric by the Real Madrid medical department, he has been diagnosed with a contusion to his right quadriceps," a statement from Madrid read.
"His recovery will continue to be assessed."
Zinedine Zidane's side resume their LaLiga campaign with a trip to Mallorca on Saturday.