Hanover 96 revealed that defender Timo Huebers had tested positive for COVID-19, saying in a statement that they insisted that no further infections were expected, as Huebers had avoided contact with his colleagues.
Their full squad and training staff were however being tested as a precaution.
"As soon as he found out that someone with whom he had been at an event was tested positive, Timo went straight to the doctor and put himself into isolation," said Hanover's sporting director Gerhard Zuber.
Leipzig's announcement that their clash with Freiburg would be closed to fans comes after similar announcements involving title rivals Bayern Munich and Borussia Moenchengladbach earlier on Wednesday.
"Despite very few infected people in the Leipzig area, we want to minimise the health risk," said sporting director Oliver Mintzlaff in a statement.
Leipzig allowed fans to attend their Champions League victory over Tottenham on Tuesday night, even after authorities elsewhere in the country ordered stadium closures.
As the number of confirmed infections in Germany continues to rise, federal states in the country are taking measures to cancel public events and slow the spread of the virus.
On Sunday, German health minister Jens Spahn called for all events with more than 1,000 people to be cancelled "until further notice".
But the decision to close stadium doors rests ultimately with regional authorities and is made on a case-by-case basis.
Fans will also be absent for Bayern Munich's visit to Union Berlin on Saturday, after officials in the German capital ordered the club to close its doors on Wednesday.
Elsewhere, Eintracht Frankfurt announced Wednesday that they would play their Bundesliga home clash with Borussia Moenchengladbach on Sunday without fans.
Yet in a joint press conference with city health officials, the club also said that the stadium would remain open for Thursday's Europa League clash with Swiss side Basel.
Moenchengladbach's home ground is in North Rhine-Westphalia state, where the biggest number of coronavirus infections in Germany have been reported.
Of 1,296 infections across the country, 484 were registered in the state, which is Germany's most populous.
Other games affected in North-Rhine Westphalia this week include the Ruhr derby between Borussia Dortmund and Schalke and the Rhine derby between Moenchengladbach and Cologne.
The latter game, scheduled for Wednesday night, will be the first in the history of the German league to be played without fans.