One by one, they rose to their feet, the roar of 11,000 people growing and growing until it sounded like rolling thunder. Americans, Europeans, Africans, Australians and Asians -- people from countries all around the world -- could hardly believe what they were witnessing.
Even though they had seen this before from Phelps, watching yet another stunning performance by the best swimmer in history never ceases to amaze.
When Phelps touched the wall in 1 minute, 42.96 seconds, nearly a full second faster than his old world record, he simply raised his right finger in the air and shook it a few times, offering a half smile in response to the booming applause.
Even he had trouble comprehending what he saw on the scoreboard. Did he ever, in his wildest dreams, think the world record in the 200 freestyle would be under 1 minute, 43 seconds?
"Nope," Phelps said, laughing as he thought about it. "Not at all."
So even you were surprised with how fast you went?
"A little bit, yeah," Phelps said.
The win earned Phelps his third gold medal and third world record in as many days at the 2008 Olympics and gave him nine gold medals for his career, tying him with fellow American swimmer Mark Spitz, U.S. track star Carl Lewis, Soviet gymnast Larysa Latynina and Finnish runner Paavo Nurmi for the most gold medals of all time.
It also got him one step closer to Spitz's record of seven gold medals at the 1972 Olympics in Munich and allowed him to check off yet another personal goal. The 200 freestyle is the one individual event Phelps did not win at the 2004 Olympics.
"It was a little bit different [this time]," Phelps joked.
In Athens, he finished third behind Australia's Ian Thorpe and Pieter van den Hoogenband of the Netherlands, but the bronze medal might have been the best possible outcome that day. It motivated him like few races ever have.
"I just hate to lose," Phelps said.
Park Tae Hwan of Korea and American Peter Vanderkaay finished with silver and bronze this time around, but neither challenged Phelps at any point in the race. He surged ahead at the beginning and never took his foot off the accelerator.
"I wanted to jump on the first 100 just to see what happened," Phelps said.
Before Athens, Phelps had never lifted weights because his coach, Bob Bowman, was worried about his potential for injury. Phelps is double-jointed in his elbows, knees and ankles and, as a result, frequently awkward on land. Bowman doesn't even allow him to jog because of his propensity for tripping over his own feet. In the pool, he had speed, but mostly because he could swim at a steady pace over a long distance.
But after 2005, Phelps began to put in grueling hours in the weight room with the goal of showing he could be a sprinter, as well. Three times a week, after intense two-hour sessions in the pool, he would head to the weight room in Ann Arbor, Mich., and grind through an hourlong workout with weights. It paid off at the 2007 FINA World Championships in Melbourne, Australia, when Phelps shocked everyone by not only winning the 200 freestyle but also breaking Ian Thorpe's world record with a time of 1:43.86.
On the medal stand that evening in Melbourne, van den Hoogenband -- who has won two gold medals in the 100 freestyle -- asked Phelps a question: What was your best time before today?
"Um ... 1:45," Phelps sheepishly admitted.
Thorpe's record had stood for six years until Phelps broke it. It was, until that point, widely considered almost untouchable, perhaps the most impressive mark on the books.
"I thought the 200 freestyle record by Ian would last for 10, maybe 20 years," van Den Hoogenband said that day.
The race in Melbourne essentially chased van den Hoogenband from the event. He dropped it days before the Olympics, knowing there was little point in wasting his energy. Phelps is simply swimming at a higher level than anyone ever dreamed. His time today was 1.10 seconds faster than the mark Thorpe set in Fukuoka, Japan in 2001 that seemed to be unbreakable.
"Phelps swam so fast," said Park, who won the 400 freestyle earlier this week, becoming the first Korean to win an Olympic medal in swimming. "It is my honor to compete with him."
Phelps, who continues to drum the athletic mantra of "taking it just one race at a time," did his best to deflect questions about whether or not he thinks eight gold medals is a possibility.
"I'm not even halfway done yet," Phelps said. "I've done everything I wanted to do so far."
He did admit that it's been hard to catch up on sleep with all the excitement of setting two individual world records as well as being a part of what might go down as the best relay finish in Olympic history.
"I have friends texting me all afternoon saying, 'I can't sleep, I'm so fired up about this race. How are you napping?' " Phelps said. "I'd respond, 'Well, I'm not napping if you're still texting me.'"
After the medal ceremony, Phelps strolled across the pool deck until he found his family in the stands. He handed the bouquet of flowers given to medal winners to his sister, Hilary. As she watched him walk away, she wiped tears from in her eyes.
It was that kind of day. Didn't matter if you were a fan, a friend, a competitor or even a big sister, you couldn't help but feel a little bit awed.