Updated

Italian Flavia Pennetta and German round winners Sunday at the U.S. Open.

The 26th-seeded Pennetta battled past No. 13 Peng Shuai of China 6-4, 7-6 (8-6), overcoming a 5-0 deficit in the tiebreak.

Pennetta swatted nine aces and broke her opponent's serve six times en route to reaching the quarterfinals at the year's final Grand Slam for the third time in her career (2008-09).

The 29-year-old Pennetta will next face Kerber, who handled Romanian Monica Niculescu 6-4, 6-3.

Russian Vera Zvonareva, last year's runner-up to Kim Clijsters, will take on No. 22 German Sabine Lisicki in the night session finale at Arthur Ashe Stadium. Eighth-seeded Australian Samantha Stosur and 25th-ranked Russian Maria Kirilenko will meet this afternoon.