Sergio Ramos could be forced to retire due to a persistent calf complaint.
The 35-year-old - who joined Paris Saint-Germain from Real Madrid last summer - has made just five appearances in all competitions this season because of muscular problems.
Ramos has been plagued with injury problems during the last 18 months, managing only 15 La Liga outings last term and missing Euro 2020 due to a lack of minutes.
His fitness woes last season included two significant muscle strains, tendon irritation and a torn meniscus - failing to feature for his former employers after March.
Ramos has already enjoyed a long and successful career, making more than 900 professional appearances for Sevilla, Real, PSG and the Spanish national team.
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And, according to French outlet Le Parisien, he's considering handing up his boots as a result of his body's wears and tears.
"The injuries are very difficult because you can never predict how they will evolve," revealed Jean-Marcel Ferret, the French national team's former doctor.
"It's all about the configuration of the calf muscle.
"You have to consider how the muscle has aged given the blows Ramos has taken in his career while playing at the highest level for 19 seasons and how much that has weakened his calves."
The injury in question is known as "old calf syndrome", as Ferret believes the defender's calves may have lost their flexibility and become more fragile.
Ramos is one of the most decorated players in history, winning five La Liga titles, four Champions League, two European Championships, the World Cup and other honours.
"He is training well," said PSG manager Mauricio Pochettino when asked about the player's fitness in November.
The former Tottenham boss added: "A world champion like him, such a competitive character, it is difficult to maintain his level of output without getting game time.
"But he is working very hard and he has a very strong will."
Ramos scored his first goal for PSG in their 4-0 win against Reims last month, helping the team move 11 points clear of rivals Nice at the top of Ligue 1.
"I'm very happy for this victory and for my first goal with this team," he said after the match.
"I'm happy to have played 90 minutes. I like to have the support of the public. It's my first goal with PSG and I hope there will be many more.
"It's important to build up habits and routine. I've been back with the group for three weeks and I'm getting into the rhythm.
"I'm very happy because I've been away from the pitch for a long time, which is my home. I feel very happy.
"Regarding the city of Paris, I feel better today because I had spent a lot of time in Madrid before. It was hard at the beginning but now I feel a little better."
