It's clear after a stunning 400 IM: This is not the Phelps of yore

But more than any of this esoterica, to the broad audience that knows Phelps as the Subway pitchman/Aquaman celebrity/TMZ target who emerges every four years to take up a place in living rooms across America as the star of a weeklong mini-series on NBC, this was his re-emergence on the Olympic stage. And it was a very different Phelps than the one who won eight gold medals in Beijing (and came to London with 14 gold medals and 16 medals in all, the second most in history). This Phelps struggled even in the opening leg, and fell further behind with each stroke: third after the backstroke, fourth after the breaststroke and then, most jarringly, a fading, struggling fourth after the finishing freestyle. This Phelps looked a little like Joe Montana playing for the Chiefs or Michael Jordan for the Wizards.

More than four seconds in front of Phelps, teammate Ryan Lochte, the other half of a wildly hyped rivalry, swam away to a gold medal in 4 minutes, 5.16 seconds, the second-fastest time in history. It was more than a second off the world record that Phelps set at the 2008 Olympics, but in the apples-and-oranges world of swimsuit technology, it was the fastest time by any swimmer in the event since high-tech suits were banned early in 2010. It was the fourth career gold medal for Lochte, 27, and his seventh medal overall, and his winning margin of 3.68 seconds was the largest ever in an Olympic 400 IM, exceeding Phelps's 3.55-second margin in 2004.

And in just those four minutes, the swim world was tilted ever so slightly on its edge. Swimming cognoscenti had expected that we would see a different, less dominant Phelps in London than the machine who tore up Beijing, and that Lochte would challenge Phelps's status at the top of the sport. After all, Lochte had beaten Phelps handily in the 400 IM at the U.S. Olympic Trials last month in Omaha, Neb. But the decisiveness of Phelps' defeat was jarring, even more surprising than the margin of Lochte's victory (3.68 seconds over silver medalist Thiago Pereira of Brazil).

"It's weird," said Lochte afterward. "Not having Michael next to me on the medal stand." And later: "I'm really surprised. When Michael swims, he's always on the medal stand."

Their plotlines will now continue on separate arcs, intersecting once more in Thursday night's 200 individual medley. Lochte chasing his own greatness, after so long chasing Phelps. Phelps, even more intriguingly, after saying this week, "It's really how many toppings do I want on my sundae," trying to avoid ending his Olympic career -- undeniably one of the greatest by any athlete in any sport -- with very public disappointment. "It's really frustrating to start out on a bad note," Phelps said after Saturday's loss, the first time he has finished off the podium in an Olympic final since he was fifth in the 200 butterfly in Sydney as a 15-year-old in the summer of 2000.

Phelps has three individual races remaining. He is solidly the favorite in the 200 butterfly (Tuesday) and a less heavy favorite in the 100 butterfly (Friday). Lochte must now be considered the favorite in the 200 IM. Lochte also has a total of three individual races left and is potentially the favorite in all three. Phelps is expected to swim in three relay events; Lochte might, as well. Both are expected to swim Sunday night in the 4x100 freestyle relay. Lineups have not been announced.

Phelps had famously taken off roughly two years from heavy training while soaking up the considerable glow from Beijing. Even when he committed to returning to swim in London, there was doubt about his ability to regain fitness. Those doubts were assuaged somewhat by his performance at the U.S. Trials, where he won four events. But a red flag shot skyward Saturday morning when Phelps narrowly avoided missing the 400 IM final, finishing as the No. 8 qualifier, just .07 in front of 2008 silver medalist Laszlo Cseh of Hungary.

"I thought he was OK," said Phelps' longtime coach, Bob Bowman, of the morning struggle. "He didn't look that great, but he didn't try that hard. Those guys [Phelps and Cseh] kind of lulled each other to sleep. I thought he would be okay tonight."

Yet Phelps was off from the first leg, trailing Lochte by .32 seconds after 100 meters. By the end of the backstroke leg, which is Lochte's strongest stroke, Phelps had fallen to third place, 2.54 seconds behind Lochte and .23 behind Kosuke Hagino of Japan. Phelps lost nearly two more seconds to Lochte on the breaststroke leg, falling to fourth place, and in the final 100 meters of freestyle, with no shot at swimming down Lochte, he failed to catch Pereira or Hagino, who took the bronze medal.

"I mean, just a crappy race," said Phelps immediately after his swim. "I saw Thiago out there [in the last 100] ... they just swam a better race than I did, they swam a smarter race than I did. In the end, they were more prepared. It's frustrating, sure. The biggest thing is to get past this and move forward. I have lots of other races. We can finish a lot better than we started."

(Phelps did not pointedly praise Lochte in his brief meeting with media after the race, a session that lasted only one minute, 43 seconds. However, Lochte said, "When we were in the back, he came up and congratulated me. He said he was proud of me.")

It looms possible that with Phelps' shortened preparation, the 400 IM is just too much race.

"I honestly don't think it's a fitness issue," said Bowman, assessing Saturday's race. "[But] in the long run, it is a fitness issue over what he hasn't done over four years."

Phelps's time of 4:09.28 was 1.39 seconds slower than he swam in Omaha at the Olympic Trials.

It will be intriguing to see how that shallow preparation affects Phelps over the next seven days. In Beijing, he had prepared relentlessly for the four years following his 2004 disappointment [relative term] in Athens, when he won six gold medals and two bronzes.

"A lot of people say Michael is inhuman," said Lochte Saturday night. "But you know what? He trains harder and he knows how to win. You have to find ways to beat him."

In the run-up to London, Lochte had been widely anointed as more marketable than Phelps, owning magazine racks with a succession of crossover covers like Vogue. But in the rush to call Lochte the Sexiest Swimmer Alive, his passion for gold might have been overlooked. It's a cliché, but applicable here: Phelps left Beijing with the biggest gold-medal haul in Olympic history. Lochte, who twice took bronze medals behind Phelps' golds and was eclipsed by Phelps's stardom, left China with motivation.

"I've said this before: This is my year," said Lochte after the 400 IM. "I know it and I feel it. Just because I put in the hard work. I've trained my butt off for four years."

It is early yet. Phelps could win several gold medals before London.

"I know he gave 110 percent," said Lochte. "The next race he's in, he's going to light it up."

The old Phelps would; we know that. This one? It will be fascinating to watch for the rest of the week.