The former Hungary goalkeeper, who made his name in the English Premier League, passed away Thursday.
He was diagnosed with cancer in 2013, but had hoped to resume his career after having a tumor removed from his arm after his last active season, at Greek club Asteras Tripoli.
a writer for Hungarian newspaper Nemzeti Sport, recalls a press conference in October 2013 where Fulop -- who played for his country 24 times -- spoke of being symptom-free and positive of his chances.
"Marci was a popular footballer in Hungary," Szeli told CNN.
"It hasn't been a regular occurrence that a Hungarian player has spent so many years playing in England, so he was appreciated professionally.
"Also he was a quiet, nice person. He didn't lead a celebrity lifestyle, there were no controversies surrounding him."
The news has hit Hungary hard on a day where its nation's footballers are preparing for the European Championship playoff tie against Norway. The first leg is in Oslo Thursday, with the return in Budapest on Sunday.
"I'm sure the members of the national team are devastated," Szeli added.
"Many of them were really good friends with him; of course, it's hard to say if it will have an effect on them."
After starting out at MTK Budapest, Fulop moved to England in 2004, joining Tottenham.
While he never established himself as first choice at White Hart Lane, he went on to impress in his 2007-10 spell at Sunderland, having earlier played for the club on loan.
He also enjoyed loans at several other teams, including Leicester City, Manchester City, Ipswich Town and West Bromwich Albion.
But it was at Sunderland, which invited him to watch its 2013 League Cup final against Manchester City at Wembley, where he made the biggest impression.
"We are devastated to hear of Marton's passing," the northeast club's chief executive Margaret Byrne said in a statement.
"He was a genuinely lovely man, liked and respected by everyone at the club during his four years with us.
"It is desperately sad when we lose a member of our Sunderland family but to lose one so young and in such circumstances is simply heartbreaking.
"The thoughts and prayers of everyone at the club are with Marton's family and friends at this terribly sad time."
The news of Fulop's death, which was reported by MTK Budapest on its website, shocked football fans around the world.
Former teammates such as ex-Sunderland defender Danny Higginbotham and goalkeeping colleague Ben Foster, who knew Fulop from their time together at West Brom, took to Twitter to pay tribute to their friend.
His former clubs also paid tribute on Twitter and sent condolences to Fulop's family.