Venus and Serena Williams continue to solidify their status as the most successful sister act in sports.
Which players do the Williams sisters regard as the best they've ever faced?
Given the fact both Venus and Serena have played the best of the best of each generation for the past two decades, it's not a question that's easily answered.
Both Venus and Serena named two Hall of Famers who have hit the courts in Indian Wells this week, Martina Hingis and Lindsay Davenport, as the best non-Williams opponents.
Both Grand Slam champions have been busy in the desert.
Hingis has partnered Sania Mirza to the BNP Paribas Open doubles semifinals. Davenport, who made her on-court coaching debut with charge Madison Keys earlier this week, covers the tournament daily as a Tennis Channel analyst.
Asked to identify the best non-Williams opponent she faced, Serena paused as if preparing to hear the "Final Jeopardy" song while running through leading candidates in her mind.
Eventually, Serena named four players: Davenport, Hingis, Steffi Graf, whom Serena beat to win her first Indian Wells title in 1999, and Monica Seles. Former No. 1 Seles has cited Serena the greatest player of all time.
"Okay. I have played a lot of people," Serena told the media in Indian Wells after defeating Sloane Stephens. "I'm like... I have a whole load of people. Let me think. I'm starting in the '90s and thinking in the '90s and then 2000s. It's so hard to say. I have played so many great players from Hingis to Davenport, Monica, Steffi. I have played some unbelievably tough players. It's a weird position.
"I think I have been able to play so many different generations that I don't think I could just give one answer. I have played Henin, who has been amazing. Monica was great. Lindsay. Hingis, she was also a super tough opponent.It's kind of hard to just say one person."
A 17-year-old Serena defeated then world No. 1 Hingis, 6-3, 7-6 (4) to capture her first career Grand Slam championship at the 1999 U.S. Open. Serena held a 7-6 career edge over the Swiss Miss.
In an interview with Tennis Now earlier this month, Venus said she regards Serena, Hingis and Davenport as her greatest rivals.
"You know what? I think that I played Martina and Serena and Lindsay the most so those were my greatest rivals," Venus told Tennis Now.
Hingis' creative court sense, flair for finesse and ability to create absurd angles were elements of the distinctive style that made her the youngest world No. 1 in tennis history. One of the few players to hold the singles and doubles top spot simultaneously, Hingis has said both sisters were her toughest rivals and called Venus her favorite rival.
"I liked playing Venus. I think it always brought out the best in both of us," Hingis said. "Serena is one of the only top rivals of my time that I don’t have a winning record against. We had some great matches. Lindsay is another one where I started off pretty well against her and then she started beating up on me—she’s four years older than me—(laughs) and then it got kind of even at the end.
"I would say the toughest rivals for me were players who had big serves and could hit winning shots off the first ball. Those were the type of players I can honestly say I really don’t like facing. You have to be 100 percent at all times to deal with those kind of players."