The rival question came up again this week in Miami immediately after No. 1-ranked Serena Williams defeated Maria Sharapova, 6-4, 6-3 in a Sony Open semifinal on Key Biscayne.
Serena Williams -- By The Numbers
SERENA BY THE NUMBERS
3 -- Family Circle Cup titles won
58 -- Singles titles won as a professional
54.6 -- Career earnings in millions of dollars
183 -- Weeks ranked No. 1 in the world
It was a somewhat entertaining match. It was wholly predictable. Sharapova, a perfectly capable woman with four Grand Slam singles titles, has lost 15 straight matches to Serena.
The dominance is similar at the Family Circle Cup, where 2014 main draw play opens Monday on Charleston's green clay. Williams has won back-to-back titles.
"And Serena won the 2008 title here and didn't play at the Family Circle Cup from 2009 to 2011," Family Circle Cup tournament director and general manager Bob Moran said. "That means she's won 15 straight matches here."
Serena goes for the Daniel Island three-peat next week.
Most of the great players had a tennis nemesis. Martina Navratilova and Chris Evert for a long time. Pete Sampras and Andre Agassi. Steffi Graf and Monica Seles, at least for a little while.
Serena Williams, 32, has been No. 1 for 183 weeks of her career. She was asked if she wished she had an arch-rival.
"I mean, everyone I play always plays me hard," Williams said, "so I feel like every match I play, I literally have to be on my best. So for me, I take a rival as every match, and I think that's one of the best ways to take it."
Serena vs. Venus
The mindset worked during an odd, rugged road to the 2013 Family Circle Cup championship. It was an endurance test even before Serena dropped the first set of the final to Jelena Jankovic before rallying for a 3-6, 6-0, 6-2 victory.
Rain delays forced a fabulous quadruple-header Friday in which the stadium court featured Serena Williams and Venus Williams winning third-round matches followed by Serena and Venus winning quarterfinal matches. Serena beat Mallory Burdette and Lucie Safarova; Venus defeated Vavara Lepchenko and Madison Keys.
"For a promoter to put up 'Serena Williams first on stadium court today, Venus Williams second, Serena Williams third, Venus Williams fourth' was something that will never happen again," Moran said.
The players got a kick out of it, too.
"Today was the day to have a ticket," Keys said.
Serena didn't lose a set.
"It was pretty awesome," she said. "A pretty intense day."
The Serena-Venus semifinal was a Family Circle Cup first. Serena's easy 6-1, 6-2 victory gave her a 14-10 lead in the sister rivalry.
A record crowd of 9,538 looked on.
"There was a buzz in the stadium I've never felt before," Moran said.
In Miami this week, Williams was asked if Justine Henin - the 2003 and 2005 Family Circle Cup champion - was her toughest foe.
Serena, with no hesitation: "Venus. Please."
120 mph serves
This year, Serena must navigate a main draw board featuring four former Family Circle Cup champions: Venus, Jankovic, Samantha Stosur and Sabine Lisicki.
Anyone who takes the court against Serena will have to face roaring right-handed power.
"I hadn't been serving great too much this tournament, and then I started serving a lot better," Williams said after the Sharapova match on Thursday. "I was hitting 120 (mph). I was like, 'Whoa. Is that me?' She actually was getting them back, too. I usually don't hit in the 120s like that. I was a little surprised. I wasn't trying to hit it that hard. I was definitely feeling pretty good about my serve, which made me feel good."
Evert won five Family Circle Cup titles in a row from 1974-1978 when the tournament was held on Hilton Head Island. Later, Tracy Austin, Navratilova, Evert (again), Graf, Gabriella Sabatini and Conchita Martinez won back-to-back Family Circle Cup titles.
A three-peat for Serena Williams would be just fine with many Charleston fans who like Williams for her play on the court and local charity work, including appearances at clinics and community events.
"It would be great for the tournament," Moran said. "There's no question that in this snapshot of an era, Serena's the best player in the world. To have her as our champion possibly three years in a row would be unbelievable."
Follow Gene Sapakoff on Twitter @sapakoff