Roger Federer and Novak Djokovic both survived after getting tough battles from their unheralded opponents. Federer came back to win in four sets after losing the first set to Belgian lucky loser David Goffin.
Djokovic had to rally from two sets down to defeat Andreas Seppi.
Here's a look at how these and other upsets will affect the rest of the tournament.
Why She Won: Azarenka is notorious for issues with managing her anger. As the match slipped away, Azarenka smashed a few racquets and seemed resigned to her fate.
Cibulkova won the match despite an abysmal first serve. She was only able to get in 47 percent of her first serve. Her return game was outstanding, though. She won 52 percent of the points on Azarenka’s serve and was 6-for-11 on break points.
Cibulkova also hit 28 winners to just 20 unforced errors to 19 and 25 for Azarenka.
Who Benefits: Samantha Stosur is the immediate beneficiary. Instead of having to face the World’s No. 1 player, Cibulkova is up next for the Aussie.
This will be the fourth quarterfinals appearance in a slam for Cibulkova and the fifth for Stosur. Stosur won the U.S. Open last fall and was runner-up in Paris in 2010.
Cibulkova reached the semifinals in Paris in 2009, her best result in a Grand Slam.
Shvedova had to come through three rounds of qualifying just to get into the main draw.
Why She Won: Her ability to keep her errors to a minimum and more consistency on her serve. Li committed 41 unforced errors to just 21 for Shvedova. Shvedova also won 50 percent of the points on her second serve to just 34 percent for Li.
Who Benefits: Petra Kvitova. Instead of playing the No. 7 seed and defending champion Li she now plays qualifier Shvedova.
With a win, Kvitova will reach the semifinals for the third time in the last four Grand Slams. The exception was her first-round ouster at last year’s U.S. Open.
Why He Won: Djokovic showed a lot of resolve by rallying from two sets-to-none down to advance to the quarterfinals. Although he won, his early deficit was one of the most shocking results of this year’s French Open.
The biggest difference in the match was Djokovic’s consistency. He had a 63 percent first serve percentage to Seppi’s 55; the Djoker won 69 percent of the points on his first serve to just 57 for Seppi.
Djokovic won 44 percent of the points on Seppi’s serve, while the Italian won just 33 percent on Djokovic’s serve.
Looking Ahead: The world’s No. 1 will next face Frenchman Jo-Wilfried Tsonga. They have split 10 meetings in their career. Tsonga won four of the first five meetings.
Djokovic’s first Grand Slam title was a victory over Tsonga in the 2008 Australian Open final.
When the lucky loser Goffin captured the first set, the eyes of the tennis world responded with shock from Paris. Federer rallied doing what Federer does: He used his shot-making skills and played big at the big moments.
Why He Won: Federer made big shots when he had to. He had 12 aces to Goffin’s four, had 59 winners to 40 for Goffin and was 4-for-13 on break points while allowing Goffin to break his serve only once in eight chances.
Looking Ahead: Federer next faces Juan Martin Del Potro in the quarterfinals. Federer holds an 11-2 edge in their matchups, including winning the last five.
Del Potro’s two victories came in 2009 at the World Championships and the U.S. Open final. Federer won in straight sets at the Australian Open final earlier this year.
Why He Won: More consistency. Del Potro committed 40 unforced errors to 57 for Berdych.
Who Benefits: Roger Federer. Federer plays Del Potro next. He holds a slightly better 11-2 edge over Del Potro than the 11-4 edge he holds over Berdych.
Why He Won. The biggest and most obvious reason was that Almagro broke Tipsarevic five times to just being broken twice himself.
A look inside the numbers shows that Almagro was more consistent throughout the match.
He won 77 percent of the points on his first serve, 62 percent of the points on his second serve and 42 percent on Tipsarevic’s serve. Tipsarevic could muster only 65 percent, 42 and 31 in the same categories.
Who Benefits: Rafael Nadal. Nadal is 7-0 lifetime against Almagro. Five of those matches have been on clay, including two other quarterfinal matchups at the French Open.
Almagro has only won two sets in their meetings. At their most recent meeting, at the French quarters in 2010, Nadal had to pull out the first two sets in the tiebreak before prevailing 6-4 in the third.