More than 13,000 people have crammed into Mexico City's central square to set a world record for the largest number of simultaneous chess games.
The players ranged from grand masters to amateurs and children
The mass tournament in the Zocalo beat the previous record of 12,388, set last year in the nearby Mexican city of Pachuca.
A city official said that 13,446 players had taken part.
Alongside thousands of amateurs were hundreds of grandmasters, including Russian champion Anatoly Karpov.
The grandmaster, who was a world champion for 16 years between the 1970s and the 1990s, played 25 games with local children during his visit to Mexico.
"People have interest so this is most important. Of course talented kids, they have the chance to improve their chess and to reach success in chess careers," he said.
Tables were arranged in the shape of a giant chess board
The claimed record has not yet been certified by representatives of Guinness World Records.
A BBC correspondent said that the players dressed in green and white and played at colour co-ordinated tables, so that from the air the entire square took on the appearance of a giant chessboard.
Most of the participants were Mexicans, including toddlers and grandfathers as well as national chess champions.
Huge screens in the plaza beamed a message announcing that the record had been broken.