As two of the biggest names in women's tennis, one would consider that Williams and Sharapova are automatically rivals, and given their mutual disdain for each other, one could say it might be a fierce rivalry.
However, rivalry is commonly defined as: "Competition for the same objective or for superiority in the same field", and while Sharapova and Williams are certainly both fighting for the same things – grand slams and the number one ranking – it's no longer a competition.
In dismissing Sharapova 6-2, 6-4 on Thursday, Williams completed her 17th consecutive victory over the Russian. The last time Williams lost to her Sharapova was at the season-ending WTA Tour Championships in November 2004, since then Sharapova has taken just one set off of Williams.
Speaking ahead of Thursday's match, Williams’ coach Patrick Mouratoglou was happy to talk up his charge's dominance.
"Rivalry in my opinion is when players are very close in terms of matches — 17-2 is not really a rivalry," Mouratoglou told Sportsmail.
The Frenchman added in the New York Times that "Serena simply plays tennis much better than [Sharapova] does" and that "we cannot say there is not an enormous gap in their level of play".
While Mouratoglou's comments have to be considered in the context of a frosty relationship with Sharapova, there is no denying that what he says is true.
The build-up to Thursday's match proved to be much more interesting than the match itself, as Sharapova – despite the greatest of efforts – was blasted off the court. Try as she might, Sharapova doesn't have the speed or power to match Williams, and too often she tried to beat the world number one at her own game.
After saving a match point on her own serve, Sharapova was a mere passenger as Williams stamped her authority on the clash one final time by steamrolling through the final game.
It was once again all too brutal for Sharapova.
Quizzed after the match about how she felt, Sharapova was in no mood to accept that a spot in the final four was a good result.
"Maybe if I was British, a semi-final would be incredible," she said. "I'd be on the front page of the paper. But I expect myself to be a champion of these events, and it's disappointing to come out as a loser because I know my level can be at the point of holding these championship trophies."
Sharapova is the only other active female player aside from Williams who has completed the career Grand Slam, and as a five-time grand slam winner she has certainly proven that she has the level of play to win the game's biggest events, but she doesn't have the level to beat Williams, she's not even close.