Melbourne, Australia (Sports Network) - Sloane Stephens outlasted an injured Serena Williams in the Australian Open quarterfinals on Wednesday to set up a semifinal matchup with World No. 1 and defending champion Victoria Azarenka.
The 29th-seeded Sloane Stephens reached her first career major semifinal with a 3-6, 7-5, 6-4 victory over her American compatriot, while Azarenka rolled in the semis with a 7-5, 6-1 victory over two-time Grand Slam champion Svetlana Kuznetsova.
After Williams rolled through the first set by converting the lone break of the frame, the players traded breaks in the second set to knot the score at 2-2, and then Stephens broke the third-seeded Williams two more times to jump ahead 5-3.
Stephens then had a chance to serve for the set, but a double fault led to a deuce and Williams took advantage to earn the break.
Williams, however, suffered back spasms during the game and went into the locker room to receive treatment by medical officials.
When she returned to the court, she held serve at love to knot the set at 5-5 despite losing some velocity on her strikes, but Stephens then took advantage of her hobbled opponent to force a third set.
Neither player could break the other in the third set until Stephens hit a forehand into the net after a long volley to give Williams a 4-3 advantage.
But Stephens answered with a break on an unforced error by Williams on her ensuing serve and another shot into the net by Williams put the 19-year-old ahead, 5-4, with a chance to break for the match.
In the decisive game, Williams again struggled to get her hits over the net as the five-time Aussie Open titlist's second unforced error of the frame resulted in Stephens snapping Williams' 20-match win streak.
The first match of the day did not start in Azarenka's favor, as the Belarusian fell into an early 3-1 hole in the first set after Russia's Kuznetsova was finally able to take a 10-deuce game with her first break.
But Azarenka returned the favor with a break of her own while also holding serve on her next two attempts to knot the score at 4-4.
Each player held serve over the next two games until Azarenka earned her second break of the set and then fought through another tough deuce to take the 77-minute first set.
The second set started with three straight breaks before Azarenka finally held serve at love to jump on top 3-1.
Azarenka then closed out her dominant second set with two more breaks to advance and keep her hopes of a repeat title alive.