Slovakia winger Jaroslav Mihalik is out of Sunday’s Nations League tie against Scotland at Hampden after testing positive for Covid-19.
And three members of the Czech Republic squad – who face Scotland on Wednesday – have also returned positive results.
Mihalik, who started Thursday’s Euro play-off win over the Republic of Ireland, and a Slovak staff member who was also diagnosed are self-isolating.
Slovakia are already without defender Milan Skriniar after his positive test.
The rest of the squad have travelled to Scotland for Sunday’s game.
The Czech Republic, meanwhile, are due to play Israel in Haifa on Sunday before taking on Scotland at Hampden on Wednesday.
After their squad were screened again on Saturday at their Cyprus training camp, head coach Jaroslav Silhavy and nine players have travelled to Israel.
They will be supplemented by players from the Czech top flight. The rest of the squad are awaiting test results and may rejoin their team-mates.
A makeshift Czech side lost 2-1 at home to Scotland last month after the players who beat Slovakia three days previously all went into quarantine.
Scotland, top of Group B4 with four points from two games, are without Southampton midfielder Stuart Armstrong, Arsenal defender Kieran Tierney and Celtic forward Ryan Christie for the Nations League double-header because of coronavirus issues.
The trio also missed the Euro 2020 play-off win over Israel after Armstrong tested positive, with Christie and Tierney having to self-isolating after being deemed close contacts.
Celtic and Arsenal have questioned the self-isolation rules, but national clinical director Professor Jason Leitch has told BBC Scotland that football cannot be treated as a special case.
“Test and protect has done really well,” he told Radio Scotland’s Off The Ball programme.
“The football authorities have liaised with the local health authorities and public health leaders and we’ve found the correct solutions on each of those occasions.
“I’m afraid the self-isolation of the positive cases and the contacts has to be the same in football as it is in a call centre.”