China won the gold and Japan the silver in the Olympics four years ago.
The Chinese return Beijing rings gold medalist Chen Yibing, while the Japanese are led by three-time all-around world champion Kohei Uchimura.
Zou Kai also leads the Chinese National Team. In 2008, Kai won three gold medals, and he should earn more hardware in London. Specializing in team, floor and high bar, Kai led China to a 2011 World Championship in October in Tokyo.
Yibing, the Chinese team captain, is known for more than just the rings. He has won four world titles and may be the most experienced gymnast in the field.
Uchimura seems to be the shoe-in for the all-around title on the men's end. He is a driving force on the Japanese squad.
He said he is "fed up with being second in the team event and that's what we have to overcome," in an interview with Jim Armstrong of the Associated Press.
Uchimura finished second all-around in Beijing, something he's not happy with. His claim to fame is his three consecutive world all-around victories, as he's the first man ever to do so.
"I have a lot of bitter memories from Beijing," Uchimura said to the Associated Press. "Hopefully, we can erase those memories and bring the gold back to Japan."
Not only do these gymnasts have world-class skill sets, but they also have the determination which might be a combination Team USA can't top.
Jonathan Horton, the only Team USA member from Beijing on the current roster seems to think otherwise.
"People think that China and Japan are probably going to win, but that's the position we want to be in," said Horton in an interview with Voice of America. "We want people to kind of doubt us because when you put our scores and what we're capable of on paper, we're just as good as those two teams. It's going to come down to what team has the better day in the team finals. And I think that just our heart and our passion, everything's going to come out on that day, and we're all going to have great performances."