It probably would be hard to find a more perfect pairing for the synchronized swimming duet event than Mary Killman and Mariya Koroleva, the two Americans who will be competing at the London Olympics.
Their nickname is "MK squared" because the first letters of their first and last names are the same. Mary Killman and Mariya Koroleva are as close as you can get to sharing the same birthday, with Killman born April 9 and Koroleva April 10, although at age 22, Koroleva is a year older.
They became a duet last September, only six weeks before winning a silver medal at the Pan American Games in Mexico.
Killman says the two have fast become friends.
"We do a lot of things together. We're almost like sisters," she admits. "It's kind of funny how close we are. A lot of times, someone will ask us a question and we answer exactly the same. And they're looking at us and going, 'Wait?'"
Although both swimmers live together and train in California, they come from very different backgrounds. Killman is from Texas and Koroleva is from Russia. Koroleva moved to the United States with her family at age nine, after the Soviet Union fell and her father took a job in the computer industry in California. At the time, she knew little English, but she took the chance to try a new sport.
"I just got a flier [i.e., an information sheet] when I was in fourth grade saying, 'Try synchronized [swimming] for two weeks for free.' So I said, 'Why not?' I don't know the language. I don't have any friends, really. It's a great way to meet people and try something new," she recalls. "And then it just kind of took off from there."
Koroleva's partner, Mary Killman, swam competitively before she switched to synchronized swimming. Killman was also on the U.S. synchronized team that features eight members performing in the water at the same time, but it failed to qualify for the London Olympics.
She says synchronized swimming is a very aesthetic sport, and that how you look in a number of areas - even in your swimsuit - are important.
"They judge how high out of the water you are. They judge how fast you can move," she explains. "And on the artistic side, it's how does it match the music. Do you look like you're enjoying it?"
Koroleva says perfecting routines takes long, hard hours of practice.
"People ask, 'How long can you hold your breath for?' Or you know, 'How do you do that?' And it's just a lot of training," she says. "You know you start when you're little, just doing a lap under water. And you can't even make the whole lap because your lungs can't handle it. But over time, you get used to it. So it's just a lot of years of training and repetition."
Mariya Koroleva and Mary Killman hope that all of their hard work pays off at the London Olympics. In their final competition before the Summer Games, they won the gold medal at the Swiss Open on July 1.