Vinci in US Open semis

Serena and Venus Williams prepared for their hotly anticipated US Open quarter-finals showdown Tuesday while Italy's Roberta Vinci put herself in the winner's path, advancing to her first Grand Slam semi-final.

Vinci, ranked 43rd, advanced to the US Open semi-finals by downing France's 40th-ranked Kristina Mladenovic 6-3, 5-7, 6-4 at Arthur Ashe Stadium, setting the stage for the dramatic 27th matchup between the Williams sisters.

"I'm so happy to be in the semi-final, if I play Serena or Venus, it doesn't matter right now," Vinci said.

Vinci is 0-4 against Serena and 0-3 against Venus in her career.

She becomes the lowest-ranked Slam semi-finalist since 83rd-rated compatriot Flavia Pennetta at the 2013 US Open.

Vinci reached her first Grand Slam semi-final at age 32, having lost in 2012 and 2013 US Open quarter-finals.

"It's an amazing moment for me. It's unbelievable," Vinci said. "First semi-final in my career. I'm so happy. I don't have words to say."

Mladenovic, playing in her first Slam quarter-final at age 22, made 64 unforced errors and 11 double faults in failing to become the the first Frenchwoman in a US Open semi-final since Amelie Mauresmo in 2006.