The global anti-doping agency has provisionally suspended the accreditation of Moscow's laboratory of the right to test athletes just months before the Sochi Winter Olympics.
WADA had opened disciplinary proceedings against the lab in the Russian capital because of questions over the quality of their tests and given them a deadline to improve the reliability of their results.
The Moscow lab has a first deadline of December 1 to bring in independent "quality management" experts to "allow everyone to be confident of the accuracy and reliability of results moving forward," WADA said in a statement.
That deadline will directly impact drug testing during the February 7-23 Sochi Games.
WADA has also imposed a second deadline of April 1, 2014, when the lab must ensure that programme of improvement has been "drafted, finalized, implemented and embedded."
"If the two above-mentioned conditions are fully satisfied within the specified deadlines (to which no extensions will be granted), then the above referenced six month suspension of accreditation of the Moscow laboratory shall never come into effect," the WADA statement said.
If Moscow loses its accreditation, it would not be able to test athletes' urine and blood samples for banned substances in the Winter Olympics.
That would follow WADA's revocation of the Rio de Janeiro laboratory's rights to test in August, which will force organisers to fly samples to Switzerland during the football World Cup in Brazil.
Rio is also host city for the 2016 Summer Olympics, which means the host cities of both upcoming Games will potentially have lost testing accreditation -- an embarrassment for the organising countries.