Rafael Nadal has spoken of his shock at the death of his former junior rival, Mathieu Montcourt. The Frenchman, 24, who was ranked 119th in the world, was found dead outside the door to his flat in Paris. He had just begun a five-week suspension for gambling on the outcome of other players' matches.

"This morning I woke up with one of the worst bits of news anyone can receive," said Nadal. "I heard about the death of our friend Mathieu Montcourt. I am still under shock for this. I can't believe it. I knew Mathieu since we were kids. We competed together."

The website of the French newspaper L'Equipe reported yesterday that Moncourt had died during the night, a statement that was later confirmed by the French tennis chief Patrice Dominguez. The cause of death is currently unknown, with an autopsy due to be carried out today.

Moncourt came through the junior ranks alongside Nadal, but was mainly known on the Challenger circuit. He reached the second round of the 2009 French Open, where he lost to Radek Stepanek of the Czech Republic.

"This very engaging boy, who had a strong personality and an independent character, was universally appreciated by all the French players and on the international circuit," read an FFT statement. "[He] had progressed steadily over the past few seasons and was on the cusp of the world's top 100 last month. His sudden death plunges all the tennis family into immense sadness."

"Mathieu was a promising youngster," added Dominguez. "He was very hard-working, serious and healthy. He was also a very kind and open boy. We are completely shocked. Our first thoughts go to his family."

Montcourt had initially been banned for eight weeks by the Association of Tennis Professionals last year, but this was reduced to five weeks by the Court of Arbitration for Sport in May. He was also fined $12,000 for gambling on 36 games in 2005 – although he did not bet on games in which he was playing. Montcourt was cleared of influencing the outcome of any matches.