Former Japan and Yugoslavia national soccer team manager Ivica Osim has died, Austrian club Sturm Graz, one of the clubs he piloted, said Sunday without specifying the cause. He was 80.

Born in Sarajevo, Osim leaves behind a large legacy due to the unifying role he had in Bosnia and Herzegovina and the wider Balkans region after the breakup of Yugoslavia.

A former forward who played for Yugoslavia at the 1964 Tokyo Olympics, Osim guided that country to the quarterfinals at the 1990 World Cup in Italy. After the 2006 World Cup, he managed Japan but left the post in November 2007 after suffering a brain infarction.

Manager Ivica Osim is pictured with his players after winning the Japanese League Cup with JEF United Chiba at National Stadium in Tokyo in this file photo taken in November 2005. 

Osim first arrived in Japan in 2003 to take the reins at then J-League first-division side JEF United Ichihara, now Chiba, propelling them to their first major title, the 2005 League Cup, by infusing the attacking ideology of making a "run with purpose."

After succeeding Zico as Japan manager, Osim sought to "Japanize the Japanese football" by combining their strengths in agility, discipline and organization while improving their stamina and decision-making, opting against simply imitating established European and South-American styles.

Then Japan national team manager Ivica Osim is pictured at a press conference at Nagai Stadium in Osaka in October 2007. (Kyodo)

"What I learned from Mr. Osim will be important for my life ahead, and I'll be doing my best to convey his message," tweeted former JEF and Japan midfielder Yuki Abe, who also played for Leicester City in England.

Forward Seiichiro Maki was a surprise late inclusion by Zico for the 2006 World Cup squad in Germany after he burst onto the scene under Osim at JEF.

File photo taken in July 2007 shows then Japan national soccer team manager Ivica Osim (L) giving instructions to Shunsuke Nakamura during a practice session in Hanoi for the AFC Asian Cup tournament. (Kyodo)

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"For me, Mr. Osim is my mentor not just in football but in life, too. I'll continue to try and embody what I learned from him. Please rest in peace," he said.

Under Osim, Japan finished fourth in the 2007 Asian Cup as his ideas began to gain traction. He was also becoming a firm fan favorite in Japan due to his way with words, but he was forced to exit prematurely due to health issues.

"Our sincere condolences to the family. I am quite shaken by the news of his passing. He left a deep mark in my playing career," said current Serbia manager Dragan Stojkovic.

The former Nagoya Grampus star and manager was a standout performer for the 1990 Yugoslavia team under Osim, scoring a brace when they beat Spain 2-1 after extra time in the round of 16 before going out on penalties 3-2 to Diego Maradona-led Argentina in the last eight.

Then Japan national team boss Ivica Osim (R) shakes hands with then Nagoya Grampus manager Dragan Stojkovic at NACK5 Stadium in Omiya in November 2008. (Kyodo)

"We had great cooperation. The World Cup in Italy and everything we experienced there will be a special memory. I will remember him as an intelligent man and a football strategist with great intuition," said Stojkovic.

Osim created an anecdote in Italy when a star-studded side the fans and media had been calling for was hammered 4-1 by West Germany in the opener. He reverted to his own team selection from the second game in a memorable campaign featuring future stars, such as Dejan Savicevic and Robert Prosinecki.

But despite being one of the favorites, his team could not take part in the European Championships in 1992, when Yugoslavia was being torn apart by ethnic conflict. Osim, whose family was broken up during the conflict, was in tears as he left his post in May that year as a sign of protest.

Osim also proved his prowess at the European club level, leading mid-sized Sturm Graz to the second group stage of the 2000-01 Champions League but failing to reach the last eight.

After returning to Europe from Japan, Osim worked to normalize the national association of his home nation, Bosnia and Herzegovina, which in 2011 was banned from taking part in international tournaments by FIFA due to ethnic divisions within the organization.

Osim chaired the normalization committee despite his ongoing health concerns, aiming to reconcile the association's Bosnian, Serbian and Croatian factions. His discretion and integrity demonstrated in his coaching days played a huge role in them reaching an agreement.

The ban was lifted in time for Bosnia and Herzegovina to qualify for their first World Cup in 2014, with a tearful Osim watching from the stands as they sealed their spot in Lithuania.

"We could produce something the whole nation can share together. It's very difficult to create something common in this country," he said days later.