Former world No.1 Angelique Kerber advanced to the last-16 of the US Open with a 6-3 6-4 victory over 20-year-old American Ann Li at the Louis Armstrong Stadium on Friday.
Kerber, a three-time grand slam champion who won the title at Flushing Meadows in 2016, converted four break points while Li, who is ranked 128 in the world,was let down by 28 unforced errors.
Li did however give a good account of herself, taking risks with some powerful forehand winners that caught the 17th seed Kerber off guard, but the 32-year-old German dictated play on the crucial points and was broken only once in the contest.
Kerber will next face either France’s Caroline Garcia, who knocked out top seed Karolina Pliskova in the second round, or American Jennifer Brady.
Another former champion Naomi Osaka survived a scare before grinding out a 6-3 6-7 (7-4) 6-2 victory over Ukrainian teenager Marta Kostyuk.
The Japanese fourth seed looked out of sorts in the second set tiebreaker but regrouped to secure the victory in the deciding set in a contest lasting over two-and-half hours against the 18-year-old.
Osaka, whose left leg was heavily taped after suffering a hamstring injury that forced her to withdraw from the final of a tune-up event last week, wasted little time in the decider as she went up a double break before serving out the match at love.
The 2018 winner will face either Estonian 14th seed Anett Kontaveit or Poland’s Magda Linette in the fourth round.
Croatian eighth seed Petra Martic survived another sloppy display to see off grand slam newcomer Varvara Gracheva 6-3 6-3.
Martic, who struggled through an error-riddled match against Kateryna Bondarenko in the second round, was again often her own worst enemy, allowing her 20-year-old Russian opponent to stay in the contest.
After victories over two players outside the top 100, Martic will have to clean up her play with Osaka, Petra Kvitova and Kerber lurking on her side of the draw.
American teenager Caty McNally raced past 21st-seeded Russian Ekaterina Alexandrova in a final set tiebreak to win 4-6 6-3 7-6 (7-2) in a second round match that was interrupted by rain on Thursday.