Visa and Procter & Gamble are on board as key sponsors for Yahoo’s coverage of the 2012 Summer Olympic Games, which the Web portal plans to ramp up from the 2010 Winter Games.

With NBC holding exclusive rights to broadcast the games, Yahoo creates ancillary programming on a dedicated Olympic microsite within Yahoo Sports. For the London Games, the company told the AP it is doubling its presence to 25 reporters and analysts, including former Olympic stars Dan O’Brien, Shannon Miller and Summer Sanders.

In addition to news updates and original video programs like “London Minute,” Yahoo’s coverage will also include an Olympic-themed sports fantasy sports game dubbed “London Pick 'Em”  that enables players to daily predict the outcome of various competitions.

Yahoo’s Olympic content will span the Web portal’s entire network, including streaming on Yahoo Sports Radio featuring live call-ins from London.

P&G brand Tide is already running ads for its Olympics-focused campaign asking people via Facebook what the American flag means to them. A Yahoo spokesperson said Visa, which is serving as an Olympic sponsor on the site for the fifth time, will run advertising around social media elements tied to the event. Other brands are expected to join them as the games draw closer.