In the spot, created by Abbott Mead Vickers BBDO, Beckham rides into town with four of his Manchester United teammates for a showdown with Real Madrid, which also has a sponsorship deal with Pepsi.
Other footballers to appear in the ad, called "OK Corral", are Gary Neville, Ryan Giggs, Ole Gunnar Solskjaer and Juan Veron, as well as Casillas, the goalkeeper for Real Madrid. Pepsi sponsors Beckham in a deal thought to be worth around £2m a year.
The spot begins in a bar, where Beckham's Pepsi is drunk by Casillas. The pair then step outside for the showdown, which takes the form of a penalty shootout rather than drawing six shooters. However, the ad's ending is being kept under wraps.
The ad was made in Almeira, Spain, the location of many spaghetti westerns. It was directed by Tarsem Singh, who has directed the Jennifer Lopez film 'The Cell', and the video for REM's 'Losing My Religion'.
Pepsi will launch the campaign in April. There will be a two-minute cinema-only version, as well as 30- and 60-second versions for television. The ad will also be previewed on Pepsi's football website.
At the beginning of this week, Pepsi was one of the brands criticised in a report by the Food Commission, which said that football clubs were wasting the opportunity to promote good nutrition by accepting sponsorships from fast-food and soft-drink companies.
Beckham appeared in last year's "sumo" spot for Pepsi, which coincided with the World Cup. It was later named the most talked about ad of the year in the 2002 Ads That Make News survey.
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