Having arrived at Flushing Meadows with little form to speak of, Wozniacki has been one of the stories of the opening week, following up her upset of No.9 seed Svetlana Kuznetsova with another impressive showing. The two-time finalist dissected Niculescu's unorthodox game to win, 6-3, 6-1.
As she did against Kuznetsova, the Dane delivered a tidy performance, her sprightly movement betraying no signs of the ankle injury that sidelined her for much of the spring. After trading a couple of early breaks, Wozniacki struck again to edge 3-1 ahead, maintaining this advantage - despite a fraught final service game - to close out the set.
The Romanian had failed to take a set from Wozniacki in their six previous meetings and never looked like breaking this spell, quickly slipping 3-0 behind. With the former No.1 prevailing in the battle of wills from the baseline match point soon arrived, Niculescu surrendering as a drop shot drifted tamely wide.
"I think it's fun to play against her but also really frustrating because she makes you feel like you can't play tennis," Wozniacki said. "You have to be mentally prepared to grind it out. It wasn't pretty, but I got a good workout running after her drop shots. I just need to step in and hit the ball and go for it. Otherwise, I have no chance."
Meeting Wozniacki for a place in the quarterfinals will be Madison Keys, who kept alive hopes of a maiden Grand Slam title by producing what she described as the comeback of her career. Trailing Naomi Osaka 5-1 in the final set, the No.8 seed looked dead and buried only to capitalize on some finishing line nerves to somehow turn the match around.
Serving for the match at 5-2, Osaka missed a presentable forehand volley that left her fighting back the tears. And while she regrouped admirably to force a tie-break, her moment had passed, Keys powering towards a 7-5, 4-6, 7-6(3) victory.
"Was that the greatest comeback of your career?"
"For sure, hands down." --Madison Keys #usopen
? Nick McCarvel (@NickMcCarvel) September 2, 2016