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".
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.
Meanwhile Diego Schwartzman beat US Open champion Dominic Thiem 7-6 (7-1) 5-7 6-7 (6-8) 7-6 (7-5) 6-2 in a stamina-sapping duel to reach the French Open semi-finals.
The match, played in blustery weather, lasted over five hours and featured numerous long rallies with both players breaking each other several times because of their superb return games.
The first four sets were tight before Thiem's level dropped in the decider, while 12th seed Schwartzman reached his first major semi and might now face Rafael Nadal.
The Spanish defending champion, seeking a 13th title, plays Jannik Sinner later on Tuesday on Philippe Chatrier.
Elsewhere world number 131 Nadia Podoroska says she "doesn't want to wake up" after a dream French Open run continued with a quarter-final victory over third seed Elina Svitolina.
Podoroska beat Svitolina 6-2 6-4 to become the first qualifier to make the women's semi-finals at Roland Garros.
The Argentine, 23, dropped to 508th in the world in 2018 and could not afford to travel to some tournaments.