One is a distance runner raised in California who has spent little time in Saudi Arabia but hopes to become a "big inspiration" for women in the kingdom, which severely restricts women in public life and effectively bans them from sports.
The other practices judo, but she has hardly ever left Saudi Arabia and has never competed.
While Sarah Attar was running cross-country for her high school in the United States, Wojdan Ali Seraj Abdulrahim Shahrkhani was watching judo on television and listening to her brothers talk about it.
Then one day she told her father, a judo coach and an international referee in the sport, that she wanted to train.
"She said, 'I want to be like you, I want to become very good,'" the father, Ali Seraj Abdulrahim Shahrkhani, told The Associated Press in an interview. "I said, OK, you want to train? I will coach you at home."
Saudi Arabia is allowing them to compete after the International Olympic Committee and human-rights groups put intense pressure on the kingdom to end its practice of sending all-male teams to the Olympics.
After Qatar and Brunei announced they would send women, Saudi Arabia would have been the only country with no women on the team. Instead, the London Games will be the first in Olympic history in which women are represented in every national delegation.
Women in Saudi Arabia cannot register for sports clubs or league competitions. They are banned from entering national trials, which makes it impossible for them to qualify for international competitions, including the Olympics.
Attar and Shahrkhani were entered earlier this month by the Saudi Arabian Olympic Committee. Neither technically qualified, but they received special invitations from the IOC "based on the quality of the athletes," IOC chief Jacques Rogge said.
Attar, 19, is an art student who holds dual American and Saudi citizenship. Sports was part of her life growing up in Escondido, California, but she has not raced competitively since entering Pepperdine University earlier this year.
On her own, she has run the 1,500 metres in 5:30.51 and the 3,000 metres in 11:37.41. At the London Games, she will compete in the women's 800 metres. Heats are Aug. 8, and the final is Aug. 11.
Attar has not been subjected to the restrictions that apply to women in Saudi Arabia. In a photo on the website of her high school team, she appears in shorts and a sleeveless top.
In the kingdom, women can be punished by the religious police for showing their hair in public. They could be imprisoned under Islamic law if they dared slip out of the house in sweatpants and a shirt for a morning jog.
After her inclusion on the Saudi Olympic team, Attar made a statement to the IOC wearing a long-sleeved shirt and trousers, and covered her hair. But she did not ignore the deep cultural differences between the two countries.
"It's a huge honour, and I hope that it can really make some big strides for women over there to get more involved in sport," she said.
Speaking directly to Saudi women, she added: "To any woman who wants to participate, I say 'go for it,' and don't let anybody hold you back. We all have potential to get out there and get moving."
Shahrkhani, 18, will compete in the over-78-kilogram category of judo Aug. 3. Aside for occasional two-week sessions with a female coach in Abu Dhabi and a training camp in Egypt, she has trained at her home in the Muslim holy city of Mecca.
"My daughter became very good very fast," her father said. "She has only been training for two years, though, and at the Olympics she will be competing against those who are already champions."
Women in Islamic countries are increasingly taking part in sports competitions. Afghan women box, Pakistanis play cricket, and Emiratis have taken up football and weightlifting. Iran is considered one of the growing powers in women's rugby in Asia.
Qatar, like Saudi Arabia, follows the strictest interpretations of Islam, but Qatar, a tiny Persian Gulf country, long ago pulled ahead of its more powerful neighbour to support and train women in its quest to become a Mideast sporting power.
The Saudi decision to allow women to compete at the London Games is unlikely to have much effect on women in the kingdom.
There are no laws that prohibit women from participating in sports, but there is no gym class for girls in public schools, and no women-only hours at swimming pools. Women do play football and basketball and have underground leagues.
Training in an individual sport like judo adds to Shahrkhani's courage, said her coach, Dilyara Safina.
"Wojdan is very strong, and she has a big heart," said Safina, a national coach in the United Arab Emirates who has trained with Shahrkhani in Abu Dhabi over the past three months.
"She might get worried because she has a blue belt and she will be competing against black belts," Safina said. "I hope she gets success at these games in London, because I am sure she can get a medal at the next Olympics."
Shahrkhani's parents and two brothers will be there to support her. To her father, she is already a champion.
"I am so proud to go to London with my daughter, with our country's flag," he said. "My daughter and me, we are going to make history."