PARIS -- The first tennis match they ever played, Ana Ivanovic remembers, was in a carpeted swimming pool in Belgrade, Serbia. In a 10-under tournament, 9-year-old Jelena Jankovic hammered the 7-year-old Ivanovic, 7-1.
Jankovic swears she can't recall any such match.
Thirteen years later, on Thursday, Ivanovic and Jankovic will meet on the red clay of Court Philippe Chatrier with an opportunity to become the No. 1-ranked player in the world.
The No. 2-seeded Ivanovic advanced to the semifinal match with a routine 6-3, 6-2 victory over Swiss veteran Patty Schnyder on Tuesday. Jankovic, seeded No. 3, followed several hours later, defeating Carla Suarez Navarro, a 19-year-old qualifier from the Canary Islands, by the same score. Suarez Navarro was bidding to become only the third female qualifier in the Open era to crash the semifinals, but Jankovic -- who wrote "I [heart] Paris" on her taped right forearm -- wasn't feeling an upset.
The Serbs remind folks here of the two Belgians, Justine Henin and Kim Clijsters, who came from a tiny, non-tennis power and both rose to No. 1 in the world. They didn't do this despite each other, they did it because of each other.
Does Jankovic see a resemblance?
"Yes, I think so," she said. "I think we are going to be dominating this tennis world soon. One of us will reach No. 1 soon, and then it will be depending on who is on form for the rest of the year. We push each other, and we motivate each other to be better players, for sure.
"It's great for Serbian tennis and the whole world to have new faces, to have new players and great rivalries. We will try to compete against each other the best as possible."
That they won by identical scores and Ivanovic's match lasted only three minutes longer was a nice piece of symmetry.
In business there is a principle known as dynamic tension, which illustrates the benefits of competing priorities. Competition and rivalry, if the circumstances are right, can manifest themselves in a bigger bottom line.
The same is true of tennis.
What are odds of a city like Belgrade, with a population of less than 2 million, producing two of the world's best three players? Better than you might think.
I think we are going to be dominating this tennis world soon. One of us will reach No. 1 soon, and then it will be depending on who is on form for the rest of the year.
History is littered with similar examples of an environment that, charged with competition, delivered multiple champions: the Australians of the 1960s; John McEnroe and Jimmy Connors a decade later; and the Nick Bollettieri Academy, which produced Andre Agassi and Jim Courier.
"Hey," said tennis analyst Mary Carillo, "talk to Chris Evert about Martina Navratilova. I see a thread here. Maybe you're on to something."
The Williams sisters crashed into the global tennis hierarchy from the unlikely launching point of Compton, Calif. The Bondarenko sisters (Krivyi, Ukraine) and Radwanska sisters (Krako, Poland) have also been propelled by peer pressure, as have Dinara and Marat Safin, who grew up playing in their father Misha's small club in Moscow. Lately, Barcelona, Spain, has been the lively locus of clay-court success.
While Ivanovic and Jankovic are careful to be respectful of each other in public statement, they are not best friends, nor even overly friendly. It would actually be more surprising, given the circumstances, if they were.
"When she was younger she went to America and I went to Switzerland, so we didn't really have a chance to practice together," Ivanovic said. "Now, traveling, she has her own team and I have my own team. You know, we don't just hang out."
Henin actually invited Clijsters to her 2002 wedding to Pierre-Yves Hardenne, but a year later the relationship cooled when someone in Clijsters' camp wondered publicly how Henin managed to stay on top for so long despite her slight stature.
It was appropriate that Ivanovic was the first to gain the semifinals because, despite being 33 months younger than Jankovic, she has always been a little better at the professional level. Ivanovic, 20, reached her first Grand Slam final a year ago here at Roland Garros and her second at this year's Australian Open. This is Jankovic's third Grand Slam semifinal and her second straight at Roland Garros.
Based on their history, Ivanovic will prevail. They have played six matches (not including a walkover for Ivanovic), and Ivanovic has won five, and 10 of 14 sets. In the only match played on clay, which would figure to give Jankovic an advantage, Ivanovic still won in straight sets.
Jankovic didn't seem to remember this match.
"I play a lot better on clay that I play on other surfaces," she said, optimistically. "We never -- I don't think we played on clay many times. I know how to mix up the game."
The major difference between the two is Ivanovic's size and power. At 6-foot-1, 152 pounds, she is more than three inches taller and 20 pounds heavier than Jankovic.
"She plays a different game," Jankovic said. "For me, it has been hard to follow. It's hard to read what she's going to hit, because she likes to play short points."
Jankovic, foremost a retriever, has a huge disadvantage when it comes to serving. She was broken twice by Suarez Navarro in her first four service games in the quarterfinals and three times overall.
"She wasted a lot of energy getting [to the semis]," Carillo observed. "In Australia, she talked about training more and beefing up the serve, but I don't think so. The serve is not carrying enough of the load."
Carillo sees Jankovic in the mold of Martina Hingis and Anastasia Myskina, players who won Grand Slam titles on angles and guile, but didn't serve big enough to do consistent damage.
After beating a qualifier in the first round, Jankovic revealed she had flown in a private plane to Serbia after her Sunday match to seek a doctor's help with a painful right forearm. She had treatment that night, and then early again the next morning before flying back to Paris for a light practice in the afternoon. She reported no pain against Suarez Navarro.
"I'm doing my best to hang in there," Jankovic said. "I feel a lot better."
Jankovic sounded excited about the prospect of reaching her first Grand Slam final -- and relieved that she was feeling no pain.
"I'm very motivated," she said. "I want to reach my No. 1 spot. Justine is gone. For me, the opportunity is very big."
A win over Jankovic would deliver Ivanovic into her third major final in the last five -- and represent her best chance to win. The two women who beat her in her previous Grand Slam finals, Henin and Maria Sharapova, are not here to stop her.
"I can hopefully reach another final," Ivanovic said. "And maybe even make that one more step and win it. That's for sure my goal."
Greg Garber is a senior writer for ESPN.com.