MEXICO CITY (AP) -- Thousands of school-skipping "tween" girls and their parents streamed into Mexico City's historic main plaza on Monday, hoping to get the best spots for a free concert hours later by teen superstar Justin Bieber that is expected to draw 200,000 people.
The gray and reddish stones of the plaza were covered in a sea of purple as the mainly 10 to 14-year-old crowd paid homage to what is reported to be Bieber's favorite color.
Under a hot sun, girls trundled through security checkpoints with hats and umbrellas, staking claim to some of the roughly 80,000 spots allocated in the plaza itself. Another 120,000 or more are expected to watch on giant screens erected on nearby streets.
Fernanda Gutierrez Aparicio, 13, a seventh grader at a local middle school, said she had spent a week camping out with her mother on a nearby street in hopes of being among the first to enter. She said they returned home only to bathe and look after Fernanda's 15-year-old sister, who recently underwent an operation.
But her mother, Adriana Martinez, 41, gave up on trying to get her daughter into the front rows because of the press of other fans.
"I was really disappointed. When we got up front, people were crushing you, not letting you breathe," Martinez said. Even long hours before the concert, "People were jostling each other and it got to the point that you couldn't move."
To Fernanda, it was all worth it - even missing the week of classes leading up to the two-hour concert that was to open with Canadian singer Carly Rae Jepsen and Mexican rockers "3BallMTY."
"I told my teacher that I wasn't going to school and not to expect me in class for a few days," Fernanda said, "because I was going to be out supporting my idol."
Fernanda most wanted to hear Bieber sing "That Should Be Me," which pretty much reflects her feelings about the Canadian singer.
"I want to be Selena Gomez, to be with him," she cooed, referring to Bieber's girlfriend.
Authorities said they will have more than 5,000 police on hand, partly to prevent the sort of crush that injured 40 Bieber fans at a free concert in Oslo, Norway, in late May.
"Most of the fans will be between 10 and 17 years old. There will be a lot of girls," said Hector Antunano, a city official. " We are being very careful that the majority of the police are women and we are taking precautions so that there is no rush toward the stage."
The stage where Bieber will perform is ringed by some of the most historic structures in the hemisphere: Mexico's Metropolitan Cathedral, the National Palace and the partially excavated remains of the Aztec capital, Tenochtitlan.
The plaza was created by the Aztecs in 1325 and was redrawn after the Spanish conquest of 1521. Bieber's performance has emptied the sprawling square of its normal population, heavy on tourists, street vendors and political protesters, some of whom agreed grudgingly to clear space for the concert by abandoning an encampment there after negotiations with the city government.
A similar concert in the Zocalo last month by former Beatle Paul McCartney drew 230,000 people, Antunano said, including President Felipe Calderon. There was no word Sunday on whether the president would take his family to see Bieber.