I would honestly have to give the nod to Werdum. Fedor hadn't lost in like 10 years before that.
The NCCA Men's Basketball tournament is littered with huge upsets and history making storylines on a yearly basis, and the Seahawks beating the Saints wasn't a very big surprise to anybody who was paying attention. The Seahawks are beasts when they play at home, and that wasn't the same Saints team that just won a Super Bowl the previous season.
Oh, and horse racing? Sorry, I could give two craps about horse racing. They just shoot the losers anyway.