An investigation has begun into alleged match-fixing in a French Open women's doubles first-round match, the Paris prosecutor's office has confirmed.
Officials began investigating on 1 October after suspicions of "organised fraud" and "corruption in sports".
A source close to the investigation told the BBC the inquiry focuses on Andreea Mitu and Patricia Maria Tig v Yana Sizikova and Madison Brengle.
Russian Sizikova and American Brengle lost 7-6 (10-8) 6-4 to the Romanians.
Alexei Selivanenko, vice-president of the Russian tennis federation, had told the Championat news website on Sunday in response to local reports on the matter: "As long as there are no official documents, it is too early to comment on anything. Tennis has a zero-tolerance policy for cases of this kind."
The Russian Tennis Federation had no additional comment on Tuesday. Brengle and the Romanian pair, and their respective tennis federations, could not immediately be reached for comment.
The investigation is likely to take several weeks.
The Tennis Integrity Unit and International Tennis Federation declined to comment.