SAO PAULO (AFP) ― American star Jennifer Lopez added a dash of glamour to the colorful World Cup opening ceremony on Thursday in a vivid contrast to the violent antitournament protests in the city.

J-Lo, wearing a carnival-inspired and revealing green outfit, appeared from a trapdoor along with rapper Pitbull to sing the official World Cup song with Brazilian singer Claudia Leitte.

The ceremony was held ahead of the opening game between Brazil and Croatia.

With her participation not confirmed until the last minute, J-Lo was a welcome sight as she rose up from inside a giant ball positioned on the stadium floor.

Gold-shirted fans started arriving at Corinthians Arena on Thursday morning, several hours before kick-off, and there was a huge cheer when the opening ceremony started.

Figures dressed as trees walked on stilts and children representing flowers bounced on trampolines around the huge, glowing ball in the center of the stadium.

It was not long before samba music kicked in and traditional dancers celebrating Brazil’s ethnic and geographical range took the floor.

Acrobats dressed as balls replaced the dancers and 64 children came in juggling balls on strings, to another big roar as a giant Brazilian flag entered the rapidly filling arena.

Finally the big ball opened to reveal Brazilian singing star Leitte, swiftly followed by J-Lo and Pitbull.

J-Lo, showing off her trademark Latin dance moves, belted out the official World Cup song, “We Are One (Ole Ola)” with her fellow performers before they disappeared back down the trapdoor.

Earlier, military police clashed with masked anti-World Cup protesters demonstrating a few kilometers away against the huge cost of staging the tournament.

Police fired tear gas and rubber bullets to break up an earlier, smaller protest near a Sao Paulo subway station.

All 61,600 tickets were sold for the opening match. Twelve 12 foreign heads of state were to attend the Group A game.