Manchester City and Spain midfielder Rodri could miss the rest of the season due to an anterior cruciate ligament injury, according to reports in Spain on Monday.
The 28-year-old limped off during City's 2-2 draw against Arsenal in the Premier League on Sunday after going down holding his right knee.
ESPN and Spanish sports daily Marca reported that tests on Monday have confirmed an ACL tear.
Rodri's loss would be a huge blow to City's hopes of winning a fifth consecutive Premier League title and ambitions of reclaiming the Champions League.
The former Atletico Madrid player has lost just one of his last 84 games for club and country.
He has been touted as a potential Ballon d'Or winner this year after his influential role in City's latest Premier League title and Spain's success at Euro 2024.
"Rodri is strong. He leaves the pitch in this action because he felt something, otherwise Rodri stays there," City boss Pep Guardiola said after the Arsenal match.
"He's the best holding midfielder in the world, he is a potential Ballon d'Or winner. I would love for him to win (the Ballon d'Or)."
City were already light in cover for Rodri and his absence leaves a gaping hole in the middle of Guardiola's midfield.
Mateo Kovacic has deputised in the holding midfield role early in the season as Rodri was bedded in slowly after his exertions in winning player of the tournament at Euro 2024.
Just last week Rodri had warned leading players could go on strike over an ever-expanding schedule.
He played over 5 000 minutes in 63 games for City and Spain last season.
"I don't know what's going to happen, but it's something that worries us because we are the guys that suffer," he said on the increasing physical and mental demands placed on players.
“Someone has to take care of us because we are the main characters of this, let’s say, sport, or business, whatever you want to call it.
City face Watford in the League Cup on Tuesday, little over 48 hours after the Arsenal match.