Mexico City packed for Bieber concert Pop star Justin Bieber, front, performs during a free open-air concert in Mexico City, Monday, June ...

Mexico City packed for Bieber concert

Pop star Justin Bieber, front, performs during a free open-air concert in Mexico City, Monday, June 11, 2012. (AP Photo/Alexandre Meneghini)

Canadian singer Justin Bieber performs at a free open-air concert at Zocalo Square in Mexico City June 11, 2012. REUTERS/Henry Romero (MEXICO - Tags: ENTERTAINMENT)

Fans of Canadian singer Justin Bieber react as he performs at a free open-air concert at Zocalo Square in Mexico City June 11, 2012. REUTERS/Henry Romero (MEXICO - Tags: ENTERTAINMENT)

Canadian pop singer Justin Bieber performs at a free open-air concert at Zocalo Square in Mexico City June 11, 2012. REUTERS/Henry Romero (MEXICO - Tags: ENTERTAINMENT)

Fans of pop star Justin Bieber cheer outside a hotel where Bieber gave a news conference in Mexico City, Monday, June 11, 2012. Bieber will perform in a free open-air concert tonight at the Mexico City's main historic plaza, the Zocalo. (AP Photo/Alexandre Meneghini)

REFILE - CORRECTING MONTH Canadian singer Justin Bieber performs at a free open-air concert at Zocalo Square in Mexico City June 11, 2012. REUTERS/Henry Romero (MEXICO - Tags: ENTERTAINMENT)

Thousands of "tween" girls jammed a vast square with their parents and screamed in unison throughout teen superstar Justin Bieber's free concert June 11, an event that was expected to draw 200,000 people to the historic center of Mexico's capital.