FanHouse Satoru Kitaoka

In a major upset in Japanese mixed martial arts, Mizuto Hirota defeated Satoru Kitaoka by fourth-round TKO Sunday at Sengoku IX, winning the World Victory Road promotion's lightweight title.

The battle for the Sengoku lightweight title will headline Sengoku 9 on August 2 at the Saitama Super Arena in Japan.

World Victory Road, the organizers of Sengoku, announced Friday the bout order for the event and the Satoru Kitaoka vs. Mizuto Hirota championship tilt took priority over the finals of the Featherweight Grand Prix.

We've been handing out our half-year MMA awards, so here's my take on the biggest upset of the last six months.

As is often the case in MMA, there were plenty of upsets to choose from. But at the end of the day, I had to go with Joe Warren defeating Kid Yamamoto via split decision at Dream.9 on May 26 (part one of the fight is above; part two is here.)

B.J. Penn was thoroughly manhandled by Georges St. Pierre when he tried to move up to welterweight at UFC 94, but he's still the best lightweight in mixed martial arts, and he has a big lightweight title fight against Kenny Florian coming up this summer.

On my list of the 10 best lightweights in MMA, Penn is first and Florian is fourth. Second on the list is Shinya Aoki, who is about to follow in Penn's footsteps and try moving up to welterweight, in Aoki's case to participate in Dream's upcoming welterweight tournament. The full lightweight Top 10 is below.