Real Madrid star Gareth Bale was sent home from training with gastroenteritis after concerns that the bug could spread through the squad.
The Welshman arrived for the session on Wednesday but was sent away, with forward Luka Jovic also told to stay at home as manager Zinedine Zidane looks to keep his team healthy ahead of their trip to Levante this weekend.
It leaves Bale and Jovic racing to be fit in time for the game and comes as a major blow to Madrid, who are looking to keep their place at the top of the LaLiga table with Barcelona breathing down their necks.
Bale signed for the Spanish giants in a then-world record £85million deal from Tottenham in 2013, and has won 13 trophies with the club - including four Champions League titles.
In recent seasons he has come in for stick from Madrid fans who don't believe he is fully committed to the cause amid rumours the Welshman hasn't learnt the language and isn't embracing himself in the culture.
He caused outrage after he was pictured with his Wales national side holding a flag that read 'Wales, Golf, Madrid, in that order'.
The former Spurs forward has long been linked with an exit from Madrid and reportedly came close to signing for a team in the Chinese Super League last season, only for the deal to collapse.
He was even linked with a return to north London with Tottenham in January, with his agent Jonathan Barnett rubbishing the rumours.
Meanwhile, Jovic is having a troubled start to life in Madrid after signing for £50m from Frankfurt this summer. There were high hopes for the Bosnian forward after he arrived at the Bernabeu but he has netted just twice in 23 appearances.