There's nothing like a good rivalry to get the competitive juices flowing.

At the Olympic pool in London, get ready to savor Michael Phelps vs. Ryan Lochte.

They are the world's two greatest swimmers, and their head-to-head races at the U.S. Olympic trials were downright epic. Of course, that was merely a tantalizing warmup for the events that really matter in Britain.

"I always love competition," Phelps said. "You can probably count on there being some other close races in the next couple of weeks."

Already the winningest Olympian ever with 14 gold medals, Phelps will swim seven more events in London in what he insists will be his final meet as a competitive swimmer. The 27-year-old has long stated his plans to retire as soon as his hands hit the wall for the final time at these Games.

Lochte has no plans to quit the sport, and the only parting gift he'd like to send to his friendly rival is a couple of Olympic silver medals, which is actually a color Phelps doesn't have.

"It's hard to say who is the best swimmer," said Lochte, who beat Phelps twice at the 2011 world championships but lost to him three out of four times at the U.S. trials. "We're both great

While much of the attention on the men's side will focus on Phelps and Lochte, there's another American ready to break out for the women. Well, to be more accurate, for the females.

Missy Franklin is still just a girl, only 17 and looking forward to her senior year of high school in Colorado. But "Missy the Missile" won five medals at last year's worlds and is scheduled to swim a staggering seven events at the Olympics.

With her boundless enthusiasm -- just about everything she says includes the word "awesome -- and a frame that's custom-built for swimming fast -- 6-foot-1 with size-13 feet -- Franklin has a chance to be a huge star in London.

"It sounds absolutely amazing," she said. "I'm thrilled to see what's going to happen this summer."

There are other compelling stories, as well, from Japanese star Kosuke Kitajima trying to sweep the men's Olympic breaststroke events for the third straight time to sprint stars James Magnussen of Australia (like Franklin, also known as "The Missile) and the tongue-twisting Ranomi Kromowidjojo of the Netherlands (who playfully tells anyone who asks how her name is pronounced, "Just like you write it.")

But two swimmers figure to stand above all others at these Games.

Phelps and Lochte.

"Neither one of us likes to lose," Phelps said.

Phelps actually qualified in eight Olympic events, giving him a chance to match his record haul of gold medals from the Beijing Games four years ago. But he dropped the 200-meter freestyle, believing a slightly smaller program would give him a better chance to succeed, considering he didn't train nearly as hard for these Olympics as he did leading up to 2008.

Plus, racing seven times instead of eight removes any pressure to repeat his Great Haul of China, when he broke Mark Spitz's iconic record for most golds at one Olympics.

"We won't hear that number `eight' again," said Bob Bowman, Phelps' longtime coach.

That leaves him with two races against Lochte: the 200 and 400 individual medleys. The laid-back Floridian, known for his wild wardrobe, gaudy jewelry and blurting out nonsensical words such as "jeah," won both events at the 2011 worlds, beating Phelps with a world-record time in the 200 and easily taking the longer race with Phelps sitting out.

Phelps, the two-time defending Olympic champion in both, returned to the 400 IM only this year after vowing in Beijing to never swim the grueling race again. Lochte beat him by a fairly comfortable margin at the trials, but Phelps came back to win the 200 IM -- the two swimmers never more than inches apart, swimming virtually in sync for all four laps.

Look for more of the same in London, especially since Phelps has clearly been paying attention to Lochte's repeated declarations that "this is my time."

"I'm always a fan of quotes," Phelps said with a sly grin.

He also edged Lochte in the 200 free at the trials, then surprised everyone by dropping that event. That will make things a bit easier for the defending world champion, but Lochte is hardly a shoe-in against a loaded international field. France's Yannick Agnel has put up the three fastest times in the world this year, Germany's Paul Biedermann won the 2009 world championship, and there's a trio of Asian stalwarts who figure to be in the mix: Sun Yang of China, Park Tae-hwan of South Korea and Takeshi Matsuda of Japan.

Like Phelps and Franklin, Lochte is down to swim four individual events in London. He also qualified in the 200 backstroke, another race he won at worlds during a six-medal performance.

The most exciting races could come in the relays, especially the 4x100 free. Australia, led by Magnussen and James Roberts, appears to be the clear favorite. But the U.S. upset a powerful French team in 2008, a memorable race in which Jason Lezak chased down Alain Bernard on the final leg to keep Phelps on course for his record eight gold medals.

"We're not farther away from the Australians now than we were from the French four years ago," said Gregg Troy, the U.S. men's coach.

It will be interesting to see who the Americans send out on that relay. Phelps didn't even compete in the 100 free at the trials, but he's assured of being in the four-man group that swims the final. The U.S. also could insert Lochte, though he only swam through the semifinals of the 100 free in Omaha.

At the moment, Lochte is assured of just one relay in London, the 4x200 free. He definitely wants to be on another and his personal coach is Troy, who will have the final say on who to send out for the relays. That should provide some intrigue at selection time.

Even if the times don't match up to the Australians, the Americans might look to gain a psychological edge by having a team that includes the world's best all-around swimmers.

"You have to have those types of guys on the relays," said Cullen Jones, another contender for a relay spot. "If anything, just to scare the crap out of everyone else. Those guys really do put forth a lot of effort, especially in the 100. Even though it's not their best event, they always show up."

Magnussen is looking to live up to his nickname. The Missile has already gone more than a half-second faster (47.10 seconds) than anyone else in the world this year in the 100 free, and he's eager to take down the world record set by Brazil's Cesar Cielo (46.91) in a high-tech bodysuit.

"If I swam it in a minute, I wouldn't mind as long as I get that Olympic gold," Magnussen said. But he added, barely pausing, "I'll be doing everything in my power to break that world record because I want to be considered the fastest man in history."

Cielo might have something to say about that, at least in the 50 free. He's the defending Olympic champion in the chaotic one-lap sprint, and he put up a blistering 21.38 at the Brazilian championships in April, just off his winning time in Beijing.

No male swimmer has ever won the same event at three straight Olympics, but it's likely to happen -- several times -- in London. Phelps has a chance to three-peat in all four of his individual events, while Kitajima is looking to duplicate his breaststroke sweeps from 2004 and 2008.

Also keep an eye on the home team.

The Brits want to improve on the six medals they won in Beijing, and they'll certainly have the crowds behind them at the dazzling new aquatic center in Olympic Park. The women, especially, will send out a strong team that includes Rebecca Adlington, who won the 400 and 800 free four years ago, and medal contenders Francesca Halsall, Ellen Gandy and Hannah Miley.

This looked to be the Year of the Comeback, with everyone from Ian Thorpe to 40-year-old Janet Evans attempting to recapture their former glory. Most failed miserably.

Thorpe was eliminated at the Australian trials, while Evans didn't come close to qualifying for the U.S. team. Former Olympic medalist Ed Moses also failed to make it, and even 45-year-old Dara Torres -- who didn't actually retire after Beijing but was trying to overcome a radical knee operation -- came up short.

Torres entered only one event at the U.S. trials, putting all her eggs in the 50 free. The made it to the final of that furious sprint, but finished fourth -- nine-hundredths of a second away from a spot in her sixth Olympics. She scooped up her 6-year-old daughter and immediately retired for the third time, this time for good.

"This is really over," Torres said.

Natalie Coughlin almost missed out, but the 11-time medalist slipped onto the U.S. team in the 4x100 free relay. That should at least give her a chance to match Torres and Jenny Thompson as the most decorated female Olympians in the country's history, but that's a far cry from the six medals Coughlin won in Beijing.

"I'm at peace with it," she said. "I did everything I possibly could this year."

Anthony Ervin only has one event, too, but his arrival in London will be much more triumphant. A gold medalist at the 2000 Sydney Olympics, he stunningly quit the sport three years later without explanation. After an eight-year walkabout, he quietly returned to the pool and quickly showed why he was considered one of the most naturally gifted sprinters in U.S. history.

Ervin completed his comeback by earning a spot in the 50 free.

"I just want to keep this fun train chugging," he said.

One thing that hasn't made much news in the lead-up to the London Games: the high-tech suits that were once all the rage.

Speedo unveiled its groundbreaking LZR Racer, developed with help from NASA, shortly before the Beijing Olympics, setting off a virtual arms race to come up with the fastest suit. The situation got downright silly by the 2009 worlds in Rome, where some swimmers competed in rubberized suits that came with everything but a motor.

After an astonishing 43 world records were set in Italy, governing body FINA finally said enough is enough. New rules were adopted that restricted suits to textile materials and limited the amount of body coverage. Since then, only two world records have been eclipsed. There likely will be more in London, but not many.

USA Swimming is eager to use the Olympics as a launching point to get over a couple of tough years post-Beijing.

The governing body was rocked by revelations that dozens of coaches, including a former national team official, had been barred from the deck largely because of relationships with underage female swimmers. That led USA Swimming to beef up its background checks, toughen the rules on what was appropriate behavior, and bring in a new official to oversee swimmer safety.

"We got thrown under the spotlight a couple of years ago," said Chuck Wielgus, the executive director of USA Swimming. "Our first reaction, quite frankly, was the reaction that a lot of individuals would have: We got defensive. We wanted to start making excuses. We got over that pretty quickly."

In addition, there was the senseless death of American open water swimmer Fran Crippen, who suffered a heat-related seizure and drowned during a 2010 event in the Middle East, leading to calls for sweeping new measures to improve safety in that still-fledgling sport.

The conditions shouldn't be nearly as harsh in London, where open water will be on the Olympic program for the second time. The competition will take place on the Serpentine lake in Hyde Park.

Russia is the overwhelming favorite in synchronized swimming, looking for its fourth straight sweep of the golds. Natalia Ishchenko and Svetlana Romashina are the world's top duet, and they'll take part in the team competition as well.

China and Spain are the main challengers.

The U.S., once a power in the sport, didn't even qualify for the team event in London. Mary Killman and Mariya Koroleva will compete in duet but are given little chance of reaching the podium after the Americans failed to earn a medal in Beijing.