Third seed Errani faced fellow Italian Karin Knapp, but showed little mercy for her compatriot as she broke serve five times in the match to come through 6-4 6-4.
The eighth seed converted all four of her break points against the Austrian’s serve and will now take on favourite Sharapova.
WTA Paris results
Alize Cornet (France) beat Barbora Zahlavova Strycova (Czech Republic) 6-3 6-7(2) 6-3
3-Sara Errani (Italy) beat Karin Knapp (Italy) 6-4 6-3
8-Kirsten Flipkens (Belgium) beat Yvonne Meusburger (Austria) 6-1 6-3
Elina Svitolina (Ukraine) beat Galina Voskoboeva (Kazakhstan) 6-1 6-2
WTA Pattaya Open
8-Peng Shuai (China) beat Alexandra Dulgheru (Romania) 6-3 6-4
5-Elena Vesnina (Russia) beat Nicha Lertpitaksinchai (Thailand) 6-3 6-3
Kimiko Date-Krumm (Japan) beat Tadeja Majeric (Slovenia) 7-6(4) 6-3