Diego Costa has tested positive for Covid-19 months after 'coughing' at reporters at Anfield during the initial outbreak of the virus.
Atletico Madrid announced the news on Thursday evening, also reporting that Santiago Arias had returned a positive test.
The pair undertook the tests themselves while on holiday, and are now self-isolating.
The La Liga club maintain that both players have been asymptomatic, and won’t being training for the new season until they have completed their time in quarantine.
A statement from Atletico read: “Today all the members of the first team passed the preliminary tests required by the protocol at the beginning of the new 2020/21 season at the Wanda de Majadahonda Sports City.
“The first team came, except for the internationals who are concentrated with their respective teams and who will be incorporated into the group's discipline as the commitments with their countries go by.
“Neither did the players Diego Costa and Santiago Arias, who underwent a PCR test on their own with a positive result during their vacation period outside Madrid.
“Both cases are asymptomatic, in quarantine and complying with the protocols of the corresponding health authorities and LaLiga.
“For this reason, both players will not be incorporated at the start of the preseason, scheduled for tomorrow September 4 at the Wanda de Majadahonda Sports City, until they complete the relevant quarantine.”
Atletico don’t kick off their season until September 27 when they host Granda.
Costa caused a stir back in March after Atletico beat Liverpool in the Champions League to progress through to the quarter finals.
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The match was controversially allowed to go ahead with a fully attended stadium despite initial concerns around coronavirus.
And former Chelsea striker Costa appeared to cough towards reporters in an attempt to avoid fulfilling his media duties.