French tennis player Mathieu Montcourt died on Monday night at the age of 24. The French tennis federation said on Tuesday that Montcourt had died overnight but that “the causes of his death are not yet known.”

“It is with great sadness that the French tennis federation has learned of the sudden death of Mathieu Montcourt,” the FFT said. “Mathieu was an enthusiastic young man, passionate, very endearing, and extremely appreciated for his kindness and politeness.”

French media earlier reported that Montcourt, ranked 119, was found dead by his girlfriend in the stairwell of his Paris apartment. No further details were given.

The FFT said only that “an autopsy will be carried out to determine the exact cause of his death,” without specifying saying when that would take place.

Last month, Montcourt achieved his highest career ranking of 104 after reaching the second round at Roland Garros. In May, Montcourt was handed a five-week ban and fined $12,000 for betting on other matches. That ban took effect on Monday. Montcourt complained during the French Open that the punishment was too harsh, saying that he never bet more than $3 at any time, and never on his own matches — a fact confirmed by the ATP.

The Court of Arbitration for Sport said Montcourt had wagered a total of $192 on 36 tennis events in 2005. It reduced his suspension on appeal from eight weeks to five.