Former Japan defender Naoki Matsuda has died aged 34 two days after suffering a heart attack during training, FIFA have confirmed.
Matsuda, who won 40 caps for his country and played for the hosts at the 2002 World Cup, was training with his third division club Matsumoto Yamaga when he fell ill.
"It is with a sad heart that I write to you today, having learned of the tragic passing of Naoki Matsuda - the legendary defender of the national team of Japan," FIFA president Sepp Blatter on Tuesday said on www.fifa.com.
"On behalf of FIFA and the worldwide family of football, I wish to extend our condolences to you, to the Japanese football community and, most importantly, to Naoki Matsuda's friends and loved ones.
"Please let them know that today the football community stands by their side."
Matsuda, who spent 15 years with J League side Yokohama F Marinos, winning the title three times, played in all four of Japan's matches at the 2002 World Cup as they reached the last 16.
His last cap came in 2005.
Matsuda died in hospital after suffering an acute myocardial infarction.
Matsuda collapsed after running with Matsumoto Yamaga team-mates in a morning session on Tuesday and went into cardiac arrest. He was taken to hospital and had been placed on an artificial respirator.
Matsuda underwent medical checks in late January when he joined Matsumoto club from Yokohama F Marinos, and was cleared without any problems.
Former Japan coach Takeshi Okada, who guided Marinos to J League titles in 2003 and 2004, said: "Matsu was in my team when we won the J League for two successive years at Marinos. He helped the team as captain for the first year as well as being a leading player. He gave me a strong impact.
"I was expecting that he would play well at Matsumoto this season. This is so regrettable."
Former Celtic and Espanyol midfielder Shunsuke Nakamura, a one-time team-mate of Matsuda at Marinos, said he hoped the 34-year-old would "watch over Japanese football", while former Japan striker Kazu Miura said: "I cannot find any words.
"He was a distinguished player who could compete at the world level."
Japan coach Alberto Zaccheroni added: "I knew he was a wonderful player as I watched his team's games last year.
"I would like to pray for the peace of his soul."
Japan Football Association honorary president Saburo Kawabuchi said he would remember Matsuda for his influence during Japan's victorious Asian Cup campaign of 2004.
"He was supporting the team as a reserve member while working so untiringly in training, and he was so happy when the team won the tournament," Kawabuchi said.
"I believe his attitude and hard work helped the team win the cup.
"I'm lost for words."
Matsuda played for Marinos for 16 seasons from 1995 to 2010, making 492 appearances and scoring 26 goals. He helped Marinos to the J League championship in 2003 and 2004.
As a mark of respect, the J League and the JFL have confirmed that players and officials will wear black armbands and hold a moment of silence at games this weekend. Flags will also be hoisted at half-mast.
Meanwhile, JFA vice-president and secretary general Kozo Tashima has revealed he will ask the organisation's medical committee to carry out a thorough investigation into the circumstances of Matsuda's death in order to take steps to prevent a repeat case in the future.
