ROME – Defending champion Maria Sharapova will take on Li Na of China in the Italian Open final after a confident 6-3 6-4 victory over Germany’s Angelique Kerber on Saturday.The Russian world number two gained revenge on 12th seed Kerber for a defeat earlier this year, overpowering her opponent with heavy groundstrokes.Li received a walkover into the final after title favourite Serena Williams withdrew on Saturday with a lower back injury.A winner in Stuttgart last month, Sharapova broke early in both sets and was never headed as she reached her fifth final of the year.Serena Williams said she expected to be 100 percent fit for next week’s French Open despite pulling out of the event on Saturday "as a precaution”."If it’s not 100 percent it’s better not to play and make it worse,” the world number six said.When she won the title in Madrid last weekend, Williams described her male counterparts as "weenies” for complaining about the slippery nature of the blue clay, saying the women were "way tougher than men”.