Tennis can be the ultimate head game.

Jelena Jankovic's unique mental approach to game is one reason why Andrea Petkovic has so much respect for good friend and sometime doubles partner.

Video: Cibulkova Smiles off Major Whiff vs. Jankovic

"What I love most about her probably is her head," Petkovic told the media in Beijing when asked about her friendship with Jankovic. "She respects everybody, but she doesn't respect anybody, if that makes any sense. But it's really nice to have sometimes."

While the former world No. 1 can sometimes delve into drama queen antics on court, Petkovic says Jankovic exudes the power of positivity off court.

"We are close friends actually, Jankovic and I. We play doubles occasionally," Petkovic said. "I love this girl. You know, she's very dynamic. She's extroverted. She's got everything going for her. I just enjoy being around her because she sort of has this positivity around her."

Both women are known as free spirits willing to speak their minds, but Petkovic isn't quite convinced they share similar personalities.

"I don't, however, think that we are that much alike," Petkovic said. "Maybe we are, I don't know. It's not up to me to judge. But I just really like her, respect her tremendously as an athlete. She does some incredible stuff, some incredible physical stuff. She was the No. 1 player in the world."

Revisit the joint interview Petkovic and Jankovic did during the Family Circle Cup in Charleston below.

Watch Jankovic pretty much run out of fingers counting down everything she eliminated from her diet, while Petkovic recounts her visit to a New York City sports bar to experience American college football amid rabid Florida State fans.