PARIS — The Paris prosecutor’s office has opened a police investigation into suspicions of match-fixing at the French Open.

The office said the investigation is being conducted by a French police unit that specializes in betting fraud and match-fixing probes and which, among other investigations, has previously worked with Belgian authorities in investigating suspected fixed matches at the lower levels of professional tennis.

But match-fixing probes targeting Grand Slam tennis are comparatively rare. The Paris prosecutor’s office said the investigation is centered on suspicions concerning one match at Roland Garros and also casting a broader look for any other evidence. It did not specify the match.

German newspaper Die Welt and French sports daily L’Equipe said there were suspicious betting patterns in the first round of a women’s doubles match on Sept. 30.

Played on Court No. 10 at Roland Garros, it opposed Romanian players Andreea Mitu and Patricia Maria Tig against Madison Brengle of the United States and Yana Sizikova of Russia.

In the match, Sizikova is broken to love serving in game five of the second set, during which she double faults twice.

According to Die Welt and L’Equipe’s reports, large sums were allegedly placed on the Romanians to win that fifth game across several operators in Paris and from different countries.

Die Welt cited unnamed insiders claiming several hundred thousand euros were bet on the game, and that the fifth game in the second was a focus of the betting — without saying specifically how much of the total betting was on that game.

The prosecutor’s office said probe was opened on Oct. 1, the day after.

The police are investigating possible charges of organized fraud and sporting corruption, it said.

The French tennis federation, which runs the French Open, referred all questions to the Tennis Integrity Unit, which oversees corruption investigations in the sport.

TIU spokesman Mark Harrison wrote in an email to the AP: “In line with the TIU policy of operational confidentiality, we are not able to comment on this matter.”