The feel-good Palestinian winner of last year's 'Arab Idol' competition kicked off the FIFA Congress on Tuesday with an impromptu call to his homeland, signing off his performance with an emphatic "Viva Palestine."
The gesture in Sao Paulo came as Israelis and Palestinians continued their stalemate over the free movement of Palestinian footballers and against a backdrop of FIFA President Sepp Blatter urging the parties to "separate politics and sports."
Wearing a Muslim headscarf around his neck, Mohammed Assaf, a young wedding singer from the Gaza Strip whose songs often touch upon the Palestinian struggle for independence, sang before world football leaders in Arabic and English.
Upon finishing his act, he abruptly asked for the microphone to thank Blatter and to single out Jibril Rajoub, the head of the Palestine Football Association, who has been sparring with Israel over the movement issue.
Late last month, in a visit to the region, Blatter said he hoped an agreement between the football associations would be "signed and sealed" before the World Cup began. All sides had a meeting at FIFA's Sao Paulo hotel on Monday but did not appear to make any significant progress.
The opening game is in Sao Paulo on Thursday, with host Brazil facing Croatia.
Palestinians complain that some of their players have faced restrictions and Rajoub has asked FIFA to suspend Israel if these are not lifted.
Israel says the restrictions have nothing to do with sport, but rather security, and accuses Rajoub of inciting against it.
Israeli Sports Minister Limor Livnat wrote to Blatter on Tuesday to defend her country's actions. She said Israel would allow Palestinian athletes to "exit and enter for the purpose of sports, excluding occasions in which there are attempts to make use of sports in order to injure or threaten the security of our citizens."
Livnat singled out the example of a Palestinian national team player, Sameh Maraabeh, whom Israel detained in late April on suspicion he met an Islamic Hamas militant during the team's training in Qatar. She alleged that the player received funds, a mobile phone and a written message from the Hamas activist. Maraabeh remains in detention.
"I am confident you will find this information worrisome and constituting clear evidence of the misuse of sports in a fashion that threatens the security of Israeli civilians," Livnat wrote.
Blatter, who says he is a "self-declared ambassador of the Palestine people" and has tried to mediate, has not responded to the letter.
Israel has cited concerns about possible attacks by Palestinian militants as the main reason for sweeping restrictions on movement that affect most Palestinians, including athletes. Israel prevents virtually all travel between the West Bank and Gaza, two territories that lie on opposite sides of Israel and are sought by the Palestinians as part of a future state. Israel captured both during the 1967 Middle East war.
Rajoub, a former Palestinians security chief, has described Israel as the "bully of the neighborhood" and urged FIFA to impose sanctions to punish Israel for its policies toward the Palestinians.
This has included preventing or delaying the entry of visiting athletes and sports delegations to the Israeli-controlled West Bank, and preventing some Palestinian players from leaving Gaza, according to Palestinian officials.
The head coach of the Palestinian national team, Jamal Mahmoud, said he was not aware of a meeting between Maraabeh and Hamas members during the team's time in Qatar. "If he did talk to a member of Hamas, it was his own individual decision," Mahmoud said.