Jadon Sancho and Roman Burki have contracted respiratory infections but both have tested negative for COVID-19, Borussia Dortmund say.
The pair will not travel to Munich for Wednesday's DFL-Supercup against Bayern Munich after developing the infections.
However, Dortmund stated via Twitter that the two players recorded negative coronavirus tests on Monday.
Sancho continues to be linked with a possible move to Manchester United but Dortmund have maintained the winger will not be sold.
The Bundesliga club are said to have set a deadline of August 12 for United to match their valuation of €120million for the England star.
With the Red Devils apparently unwilling to meet that price, they are thought to be pursuing alternatives in the market, such as Watford's Ismaila Sarr.
Dortmund won their first Bundesliga game of 2020-21, beating Borussia Monchengladbach 3-0, but suffered a 2-0 loss to Augsburg last week.
Treble-winners Bayern, who were thrashed 4-1 by Hoffenheim in their last outing, also have injury concerns ahead of the Supercup showdown.
New signing Leroy Sane is out with a knee problem and David Alaba is battling a muscle injury.