Dan and Dave. Lochte and Phelps. The Beast and the Bolt.
The first two head-to-head duels failed to live up to the hype. But Yohan Blake and Usain Bolt are more likely to deliver on the track in London.
You remember Usain Bolt. In Beijing, the only question about the 100 and 200-meter dashes was how freaky Bolt would get as he crossed the finish line far ahead of the pack. In the 2008 and 2009 World Championships, Bolt set world records as his long legs floated over the track with ease.
Last year's World Championships didn't provide any sort of conclusive evidence about him. He false-started in the 100-meter dash and wasn't able to defend his title. Then he dominated the 200-meter dash with what he called a "conservative" race.
At the time, 100-meter winner Blake was a bit of an afterthought. He won the world championship, sure, but there was a 6'5" asterisk on that title.
Then things turned interesting. Blake beat Bolt in both sprints at the Jamaican trials, some of the most competitive races outside of the Kenyan distance trials.
Feeding into the mental side: Did Blake force Bolt's false start in the World Championships by flinching?
Physical side, check. Mental side, check. That's a classic rivalry. Now can anyone get in the way?
Carl Lewis says yes. The sprint legend tells BBC that the American sprinters are going to dominate.
The charts say no. Blake, Bolt and fellow Jamaican Asafa Powell have the bulk of the top 100-meter times. American Justin Gatlin is in the mix, with Gay a little farther back along with Trinidad and Tobago's Keston Bledman.
In the 200-meter dash? The Americans aren't close.
The "Dan and Dave" rivalry fizzled when Dan O'Brien botched the pole vault in the Olympic trials (it's worth noting that for the rest of his career, O'Brien was nearly as peerless as Bolt was four years ago). Ryan Lochte and Michael Phelps have made more news in London as relay teammates than medley rivals.
Blake and Bolt? The hype will be deserved.