Finding the perfect doubles partner is like meeting a new best friend: when it happens, you just know.
"We complement each other well and we complete each other's games; we play differently throughout a match, but one can't go without the other. We have completely different personalities, so we have a lot of fun with each other. We react differently to almost every situation, and sometimes that can make things very funny!"
Known by fans as the "Silent H's," the Czechs have hardly been a quiet presence on the tennis court, having hit their way into the world's Top 4 and earning two major titles, along with an Olympic silver medal.
Hlavackova and Hradecka are back at the BNP Paribas WTA Finals Singapore presented by SC Global for the first time since reaching the final in 2012; seeded No.7, they began the week with an emphatic upset over No.4 seeds and WTA Rising Stars Timea Babos and Kristina Mladenovic - dropping just three games in less than an hour of play.
Such success contrasts a simpler start for these compatriots and childhood competitors.
"I've known Lucie since our days as kids on the Czech tour. She was always a good doubles player and we often met on opposite sides of the net."
They first joined forces to claim an indoor ITF Circuit event in the fall of 2007, and went on to win six of their first seven tournaments together - two of which were WTA titles in Prague and Bad Gastein.
"It came naturally," Hradecka recalled. "We had good results, played similar tournaments and liked playing together. So when our ranking was good enough, we decided to play big tournaments as a team."
By 2009, she and Hlavackova had played a full schedule of Grand Slam tournaments, pushing Venus and Serena Williams to three sets at the French Open. They began 2010 with a title in Brisbane, and rarely played apart for the next three years.
"What is special about being on a team with one consistent partner is that you can improve during the year," reasons Hlavackova. "You get to know your partner perfectly and you have more chances to get better and better. Our game styles match so well that we just make a good fit together."
That consistency proved key for the Czechs, who upset two of the Top 3 seeds to win their first major title at the 2011 French Open, and made three more major finals in 2012, including the Gold Medal Match at the London Olympics. Despite finishing second to the Williams sisters, Hlavackova and Hradecka hardly had time to reflect on what had been lost in the face of their momentous gain.
"We were sitting on the court and couldn't stop crying at how happy and stoked we were about an Olympic medal."
"The Olympic final in London is hard to beat," agreed Hradecka. "Winning the silver medal and the whole experience of the Olympic Games was just amazing."
Though they eventually avenged the loss to the Americans en route to the US Open title in 2013, they made the stunning decision to split later that fall.
"Andrea felt she needed a change."
"I thought it was a right decision after so many years together," Hlavackova said. "I probably needed a break to see how would go in a different team."
They captured their first titles without one another after last year's US Open, but soon realized that winning was better together, and reunited weeks later.
"At the end of season, I asked Lucie to team up together again, because I believe that together in the long run, we are the strongest team."
Their second chapter started in much the same fashion to their first, by winning an indoor ITF event last fall.
"Our first tournament together felt like we had never stopped," Hradecka admitted. "The chemistry on court was just there.
"The difference now is that we both feel more responsibility on court. I cannot really explain it, but it definitely feels that way."
With a strong foundation, Hlavackova and Hradecka enjoyed a solid season, reaching three finals and returning to the French Open semis this past spring. Finishing inside the Top 10 in the Road To Singapore standings, Hlavackova looks back on the year as one that required them to rebuild, both as individuals and as a team.
"We felt the connection on court again right away. But I believe competing at the top level and getting that confidence and respect back from other teams might have taken us the whole season."
Harmony on the doubles court has allowed for clearer focus on singles, as well. A former World No.58, Hlavackova returned to the Top 150 after qualifying for the French Open and winning her eighth career title on the ITF Circuit.
"I enjoy singles a lot, because it's just a few weeks in a year when I give it all only to that discipline. Physically, I feel good this year - especially compared to last year - so it's much more fun and like a challenge for me, to show that I can still make it in singles if I want."
Hradecka has also enjoyed the benefits of a clean bill of health; beginning the year with a bang, she upset then-No.5 ranked Ana Ivanovic to reach the third round of the Australian Open as a qualifier, rocketing up nearly 100 spots in the rankings since the start of the season.
"I changed my diet quite a bit when I began my off-season training. After a few weeks, I knew I made the right decision. I started the year ranked around No.140 so my goal was to get back into the Top 100. I was able to accomplish that and more, mainly because I stayed injury-free and healthy, something I haven't been able to manage in the last two years."
With goals of playing a second Olympic Games in Rio de Janeiro, the Czechs show no signs of slowing down, and with a berth in the semis of the WTA Finals on the line, the "Silent H's" are ready to shake up the circuit they used to dominate.
"We maximize each other's strengths, and cover up our weaknesses. Our games are similar, but still, each one of us is better at different parts of the game.
"It's a great mix."
All photos courtesy of Getty Images.