The defending champion Russian, seeded second this year, survived a nightmare start to hold on to her crown for at least another day with a 0-6, 6-4, 6-3 win over tough Jelena Jankovic in a compelling quarter-final tie.
World number three Azarenka, meanwhile, reached her first semi-final at Roland Garros when she defeated friend and former doubles partner, Maria Kirilenko of Russia, 7-6 (7/3), 6-2.
Sharapova and Azarenka have played each other 12 times with the Belarusian 7-5 ahead, although it will be their first meeting this year.
The 26-year-old Russian was all over the place for a set and 30 minutes in her match against Jankovic, but with the Roland Garros exit door beckoning, she steadied her nerves enough to apply the firepower needed to derail the Serb’s brave challenge.
“She played such a great match from the beginning and was very aggressive,” Sharapova said of her opponent.
“I knew after the first set that I had to change things around. I just had to erase the chapter and move forward. I still felt I was in the match and I broke her in the first game (of the second).
In what was a matchup of two former world number ones, Jankovic, who has clawed her way back into the world top 20 this year, got off to the prefect start with three straight breaks of serve to take the first set 6-0 in just 29 minutes.
The Russian started to find some consistency with her groundstrokes at the start of the second set and she also got help from her opponent, who served up her first double fault of the match on break point.
The match suddenly turned on its head with Sharapova dominating rallies with her heavier firepower and she eased out into a 5-1 lead before sealing the win three games later.
Australian Open winner Azarenka hadn’t faced anyone inside the top 30 en route to the last eight and that lack of sharpness was evident immediately with four breaks in the first four games.
The first set lasted a marathon 76 minutes, but once 23-year-old Azarenka had pocketed that, it was clear that Kirilenko, who needed a medical timeout after the seventh game, simply lacked the armoury to upset her bigger and stronger opponent.
The Belarusian breezed through the second set in half that time, breaking for a 3-1 lead when Kirilenko, who she had also beaten for the bronze medal at the London Olympics last year, served up a fifth double fault of the match.
Azarenka went to two match points in the eighth game and secured victory when Kirilenko hit a forehand long.
“Maria is such a great competitor and it was a really tough start,” said Azarenka.
“But I am really happy to get through to my first semi-final in Paris at the third time of asking.”
The women’s semi-finals will be held on Thursday with top seed Serena Williams taking on last year’s runner-up Sara Errani in the other match.