Real Madrid have confirmed that Uruguayan midfielder Federico Valverde has suffered a broken leg.
Valverde played 76 minutes of a La Liga clash against Valencia at Mestalla on Sunday before being replaced by Toni Kroos.
The Blancos ended up losing the match 4-1, with Carlos Soler scoring a hat-trick of penalties for the hosts, slipping to fourth in the Spanish top flight in the process.
Karim Benzema opened the scoring in the 23rd minute but the visitors fell apart thereafter, with a Raphael Varane own goal compounding a miserable evening for Zinedine Zidane's men.
Madrid have now revealed that Valverde sustained a serious injury during the weekend fixture which could see him sidelined for a significant period, but did not offer a specific timeframe for his recovery.
A statement on their official website reads: "Following tests carried out on our player, Federico Valverde, by Real Madrid Medical Services, he has been diagnosed with a fracture in the posterior tibial bone in his right leg.
"His recovery will continue to be assessed."
The Blancos midfielder will almost certainly sit out his country's next round of World Cup qualifiers, with Uruguay scheduled to face Colombia on Friday before coming up against Brazil four days later.
Valverde has played a key role in Zidane's set-up at the start of the season, scoring three goals in 11 matches across all competitions, and has now firmly established himself as one of the most reliable members of the squad.
The 22-year-old has impressed in a holding role alongside Luka Modric, but Madrid may have to make do without a key performer when they return to action after the international break.
Benzema's fitness could also be a cause for concern after he limped off late on against Valencia with an apparent hamstring strain, while Eden Hazard and Casemiro missed the trip completely after testing positive for Covid-19.
Zidane will hope his players can recover quickly over the next fortnight before Madrid take in a tricky away fixture at Villarreal on November 21, with a crucial Champions League clash against Inter at San Siro set to follow that encounter.