In the cereal cover wars, General Mills Inc. settled for silver.

The company that has been putting champion athletes on Wheaties boxes since 1934, failed to sign the greatest Olympic champion of all time: Michael Phelps.

In a public relations coup, the eight-time gold medalist at the Beijing Olympics will instead appear on rival Kellogg's Frosted Flakes and Corn Flakes boxes beginning in mid-September.

Thursday, a week after Kellogg's announced its exclusive deal with Phelps, General Mills said it had signed gymnast Nastia Liukin, who won the all-around gymnastics gold, and gold-medal decathlete Bryan Clay.

The marketing world was abuzz, wondering how General Mills could have let Phelps slip away -- particularly after his Wheaties box appearance following the 2004 Olympics. General Mills has a long track record of signing top Olympic athletes for Wheaties -- the so-called "Breakfast of Champions" -- including decathlete Bruce Jenner and gymnast Mary Lou Retton.

According to an article in Advertising Age, Kellogg had more money to lure Phelps. The paper said Kellogg spent $11 million in media on Frosted Flakes in 2007, while General Mills spent $114,000 on Wheaties.

General Mills did not return calls Friday seeking comment.

Kellogg spokeswoman Susanne Norwitz dismissed the suggestion that her company had won gold in the battle of the cereal boxes. "But I can tell you that we're proud and honored to have Michael Phelps."