La Liga president Javier Tebas has warned players could be forced to quarantine after Barcelona's Nelson Semedo breached La Liga protocol by attending a gathering of more than 20 people earlier this week at the Casanova Beach Club in Castelldefels.
Semedo was not allowed to train on Thursday and will have to wait for the results of the latest round of coronavirus testing to come back before being given the green light to return to training with his teammates.
The Barca right-back is not the first player to break the rules drawn up by the league to ensure the season could restart this week. Last month, four Sevilla players were photographed at a barbecue attended by more than 10 people.
One of the conditions the Players' Association (AFE) insisted on when negotiating the return of the competition was that there would no need for any form of quarantining between matches.
However, Tebas says he could backtrack on that agreement if players don't behave, which could see teams asked to stay at their training grounds or in hotels.
"If this continues, we could be obliged to look at something we weren't going to do, which is quarantining," he said in a video call with international media on Thursday.
"We had planned for an obligatory quarantine the week before the season began. But if this is going to become more normal -- three players from one club, one from another -- then we will be left with no choice.
"If they aren't complying with the rules with the due diligence of a footballer, then we would have to take a step back and demand they quarantine. If so many parties and so many barbecues continue...
"It would be a shame because many are complying, so I make a call to all those that are to ensure everyone at their club is following the rules. La Liga's shown a lot of confidence by not enforcing quarantine and that confidence is diluting as the rules in place are being broken."
Semedo's gaffe not only breached the rules drawn up by the league to ensure the campaign could be completed but also broke regulations in place across Spain as the country gradually opens back up.
Catalonia is currently in Phase 2 of Spain's de-escalation measures following a strict eight-week lockdown. That means no more than 15 people are allowed to gather at any one time.
A source at Barcelona said they were previously "unaware" of Semedo's actions and only found out on Wednesday. The Portugal international had trained earlier that day.
The protocol in place dictates that players are tested for coronavirus two days before each match, so the entire Barca squad underwent the latest round of tests on Thursday.
Semedo, despite isolating from his teammates, was also tested and if the result comes back negative he will be available to play this weekend.
Barca will be without Ousmane Dembele (injured) and Clement Lenglet (suspended) but have been boosted this week by the return to fitness of Luis Suarez. Coach Quique Setien said Lionel Messi will also play despite missing training last week with a thigh problem.
The league resumes with Barca two points clear of Real Madrid at the top of the table. There are 11 games to be played, with La Liga hopeful of completing the season by July 19.