Atletico Madrid will travel to Lisbon on Tuesday for the final phase of the Champions League, but the Rojiblancos will be without Angel Correa and Sime Vrsaljko after positive Covid-19 tests returned on Sunday night.
The Spanish side announced the positive tests on Sunday, but did not reveal the identities of those affected and asked for privacy.
Atleti were due to travel to Lisbon on Monday evening, but have had to change their plans in light of the test results and will now fly to Portugal on Tuesday instead.
The club have now revealed that Argentine attacker Correa and Croatian defender Vrsaljko are the two individuals who tested positive.
"The first team and members of the technical staff underwent new PCR tests on Sunday, the result of which has been negative in all of them, following the emergence of two positive cases in the tests carried out on Saturday," Atletico said on their website on Monday.
"Following the health protocol, these tests were also performed on the family members who live with the two positive cases, with all of them also negative."
Atletico returned to training on Monday afternoon without Correa, who remains in isolation at his home without presenting symptoms.
Vrsaljko, meanwhile, was recovering from an injury and is also asymptomatic.
Both players will miss Thursday's quarter-final clash against RB Leipzig and the rest of the final phase in Lisbon.
