I know, I know, a lot of things could be the difference in that quest. Phelps could fall off a curb or eat a bad dumpling. But sticking to the perils in the pool, this is Phelps' most treacherous race. Not that any gold medals will come easy, but consider the rest of his program: No one has come within a second-and-a-half of his time in the 200 free this year.
Ditto in the 200 fly. Ian Crocker still owns the 100 fly world record of 50.40, set in 2005, but Phelps has beaten him in 12 of their 16 meetings, including the '04 Olympics, the '07 world championships and the '08 Olympic trials.
Relays? The U.S. men are favored in every one. (Though with France and South Africa gunning for the Yanks, the 4x100 free relay could turn out to be the thriller of the meet.)
That leaves the two individual medleys. Phelps owns the world record in both. His biggest rival in the 200 IM, Ryan Lochte, will have swum a blistering 200 backstroke just 25 minutes before that event's final on the morning of the 15th, not enough time for him to clear the lactic acid out of his system and take the long, restorative nap that would put him on equal footing with Phelps.
The 400 IM is a different story. In that final, the first of the meet, Lochte will be just as fresh as Phelps. True, Phelps beat Lochte at the swimming trials in Omaha, Neb., in June, but he had to shatter his own world record by nearly a second to do it. And that was with Lochte favoring the ankle he twisted a few weeks earlier chasing his Doberman puppy, Carter.
Using Omaha as our guide (and not knowing what Hungary's Laszlo Cseh, who swam an impressive 4:07.96 in June, will throw into the soup), this is how the race should play out: Phelps will open a body-length lead on Lochte in the first leg, the 100 fly. Over the 100 backstroke leg, Lochte, the co-world-record holder in the 200 backstroke, will cut that lead by half. Over the next 100 Lochte, who has improved in the breaststroke even more than Phelps has in the last year, will pull even.
By then, I expect that the Water Cube's Sunday morning crowd of 17,000 to be on its feet and in a froth, watching the first swimming world record of many at this Olympic Games. Lochte will hang with Phelps for the first 50 of the freestyle. Then comes that turn.
"That last turn is brutal," said Lochte. "You're dying. The last thing you want to do is go under water. You want to come up and get air."
But dive he must. On that turn in Omaha, Phelps flipped and went deep, making six or seven powerful butterfly kicks before surfacing half a body length ahead of Lochte, who took about three kicks underwater.
"I don't think he set himself up well enough going into the turn," said Lochte's dad, Steve, a swim coach. "The idea on a flip turn is you have to set yourself going in with the proper momentum and timing in order to get the momentum off the wall. That was probably his biggest mistake of that race."
As soon as he finished in personal best of 4:06.08, .83 seconds behind Phelps, Lochte could recall a whole raft of errors that might have added as much as a second to his time.
"All my turns were just horrible," he said at the team's training camp at Stanford in July. "I couldn't really push off the wall, so I was easing into it; I wasn't attacking the wall the way I usually do. But now that my ankle is getting better, I've been working on my turns a lot more."
No doubt Phelps has been doing the same.
"He's faster than me right now," said Lochte at Stanford, where he and Phelps occasionally trained side-by-side, pushing each other in every stroke like neither one ever gets pushed by one person in practice. "I'm always going to be looking at him, and try to do what he's doing, but do it even better. So if he takes 12 kicks under water, I'll take 13 or 14. Anything to get that little edge."
Who will have that edge coming out of that final turn? History tells us it will be Phelps. But for him to win that first, critical gold, Lochte is going to make him find a gear he didn't even know he had.