Both Halep and Brianti will be chasing their first WTA title Sunday.
The seventh-seeded Halep made the most of Flipkens' weak serve to break her six times. She made the decisive break in the ninth game of the second set and served out the match at love.
"It was a difficult match, because she played a different game with slice, but I'm happy that I played good and I found the game to beat her," Halep said.
Halep lost to Iveta Benesova in last year's final after coming through the qualifiers.
Safina was set to play her first semifinal since her runner-up finish at Cincinnati in August 2009. She said on her Twitter account that she decided to withdraw because of a fever.
"It's sad because I was playing good, but health is more important," she said.