La Liga has confirmed that five players have tested positive for coronavirus.
All five unnamed players - across the Spanish league's top two divisions - are asymptomatic and in the final phase of having the disease, but will now go into quarantine and will be unable to return to group training until they have had two negative tests.
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A La Liga statement read: "After completing the medical tests on the minimum essential personnel referred by the clubs to start training, some cases of Covid-19 have been detected.
"Specifically, between the clubs of La Liga Santander (Primera Division) and La Liga SmartBank (Segunda Division), five positive cases have been detected in players, all of them asymptomatic and in the final phase of the disease.
"As planned, the next steps with people who have taken a stand for Covid-19 are: To remain in quarantine in their homes, carrying out the same individual physical activity that they have been doing until now, following the instructions of the club, for those who are footballers.
"In the next few days, they will be tested again for the Covid-19 and, after obtaining two negative results, they will be able to join the training sessions at their club's facilities.
"In addition, La Liga will offer people who live with those affected the possibility of also doing screening tests."
La Liga president Javier Tebas has said there will be football every day when the league resumes, and that La Liga and the Segunda Division will start at the same time. Tebas earmarked June 12 as a potential resumption date, but the actual return date will depend on the coronavirus situation in Spain.
Meanwhile, two players at German second division side Dynamo Dresden have tested positive for coronavirus, putting on hold the club's planned return to Bundesliga 2 action next weekend.
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Dresden were due to play Hannover away on May 17 when the top two leagues league resume in Germany after a two-month suspension, but the entire squad, coaching and supervisory staff must go into 14 days of quarantine at home.
"We are in contact with the responsible health authorities and the league to coordinate all further steps," Dynamo sporting director Ralf Minge said.
"The fact is that we can neither train nor participate in any games over the next 14 days."
A third Brighton player has tested positive for coronavirus, chief executive Paul Barber has confirmed.
It was confirmed in March that a Brighton player had tested positive after three members of the squad had shown symptoms.
Speaking to Sky Sports News, Barber confirmed a third member of the first-team group has produced a positive test despite the safety guidelines being in place.
"It is a concern," he said.
"Unfortunately we've had a third player test positive yesterday (Saturday, May 9), so despite all of the measures that we've been taking over the past few weeks, where the players haven't been involved in any significant training at all, we've still suffered another player testing positive for the virus.
"So there are concerns and I think it's normal for all clubs to have those concerns. We want to make sure we do everything that we can to ensure those protocols are in place and are safe and secure and mitigate the risk as far as we can."
Analysis from The Mirror's chief sports reporter Andy Dunn...
"I don't think the Bundesliga and Brighton cases are game changers. They are just indicative of the type of hurdles that are going to have to be surmounted if you want to get football back on. Talking about Germany, there were three players from Cologne, at the start of the month, who tested positive for coronavirus, yet they still carried on training. The local health authority gave them permission and they are scheduled to resume their Bundesliga season against Mainz next Sunday.
"Local health authorities in different regions of Germany are reacting differently. Clearly in the case of the latest Brighton player to test positive, they won't have resumed team training yet, obviously, so it might be that he just has to self-isolate.
"These are all problems and barriers that we know are going to be put up. Without doubt, we know they are going to be put up and they are going to be tough to get over, but you mention asking the question to Dominic Raab, the reason why No. 10 asked a sports reporter to ask a question at that briefing, was because they want to get out there.
"He was ready to say that they want it to come back, they want it to lift the spirit of the nation, which Culture Secretary Oliver Dowden repeated on Friday, and it's quite clear from the feedback we are getting from the government that they want this to go ahead, and the Premier League, for financial reasons, want it to go ahead.
"Basically, the will is there from the government and from football to get it back on. They know they are going to have issues like this that are going to come up every single day. Last night the Bundesliga, today the Brighton issue and they are going to have to be got over.
"Whether or not these hurdles can be surmounted remains to be seen, but the underlying point, certainly from the government this week, is that they will do all they can to help the Premier League get this back on."