The woman in blue is Karolina Pliskova, 21, of Louny, Czech Republic. She is 6-foot-1, right-handed and the No. 107 player in the world. The woman in pink is Karolina's twin sister, Kristyna. She is 6-0, left-handed, and the No. 125 player in the world.
It's Monday morning, and the Pliskovas are playing mixed doubles with their Freedoms teammates, Luka Gregorc and Jordan Kerr. Folded-up wooden bleachers surround the court, and men work nearby, hanging banners and plopping black, individual cushions on some of the seats.
The workers are preparing for Tuesday night, when the Freedoms open their World TeamTennis schedule at 7 p.m. against the Sacramento Capitals. The WTT format demands teams play five sets, each of a different format: women's singles, men's singles, women's doubles, men's doubles, mixed doubles.
Because of these rules, the sisters will both play two sets. One will play a singles set. One will play on the mixed doubles team, and they will work together on the women's doubles team. Coach Josh Cohen said Monday he won't decide the sisters' roles until hours before Tuesday's match. In the mixed doubles set, one of the sisters could team with marquee player James Blake, who is coming to town Tuesday for the match.
The Freedoms selected Karolina with the first overall pick in the WTT draft in March. In the second round, they picked Kristyna. They had to. The sisters asked to play on the same team.
"We are always together," Karolina said. "If we aren't on the same team, I don't think I want to play in the WTT."
The sisters have played tennis since they were 4 years old. Their father, a former hockey player who stands about 6-6, ushered them to the sport. He didn't push the girls to practice, Kristyna said. They took to the sport naturally. But when it came to the matches, dad watched, and he was strict. No little mistakes allowed.
Soon, Karolina said, the Pliskovas were too good for players their age. And in the Czech Republic, they weren't allowed to compete against older players. So when they were 9 years old, the girls moved to Wolfsburg, Germany, to play against 12-year-olds.
Their games have improved since. As a junior in 2010, Karolina won the Australian Open girls' title. Later that year, Kristyna won the Wimbledon girls' title. In 2011, Kristyna qualified for the Wimbledon main draw, and this year Karolina did the same at the Australian Open.
Cohen's sister, Julia, also competes on the Women's Tennis Association Tour, and the coach has followed the Pliskovas' young careers. They could be the best women's players in the WTT this season, Cohen said. They're tall, and they can pound the ball about as hard as any woman in the league.
"Tennis is a big power sport," Cohen said. "Look at the strength they have. Not everyone has that kind of power coming off their racket."
He also praised their chemistry. On most WTT squads, two women are paired together who have never played doubles before. But not the Pliskovas. They were born to play together, the right-handed and left-handed sisters.
"We know each other," Kristyna said. "I know how she thinks. With her, I'm not nervous at all."
Contact Tyler Jett at 215-854-4550 or tjett@phillynews.com