NEW YORK, NY, USA - Angelique Kerber is closing in on the No.1 ranking but her work is far from done in New York. It's quarterfinal time at the US Open! Chris Oddo previews Tuesday's action for wtatennis.com.
Arthur Ashe Stadium
 Angelique Kerber (GER #2) vs.  Roberta Vinci (ITA #8)
Head-to-head: Tied, 2-2
Key Stat: Kerber will ascend to the No.1 ranking if Serena Williams does not reach the final in New York.
Angelique Kerber continued her fine form with a straight-sets victory over Petra Kvitova on Sunday, and on Tuesday the German will look to reach her second career US Open semifinal. Standing in her way will be a tricky challenger - No.7 seed Roberta Vinci. The Italian has won 10 of her last 11 at the US Open and she has turned around an otherwise disappointing 2016 campaign here in New York. "It will be completely different match," Kerber said of facing the Italian on Arthur Ashe Stadium. "I know that I have to be ready for that. I mean, she played an amazing tournament here last year, so she has great memories and she will go for it. But for me it's important to go out there, playing my game again, and trying to take this challenge against Roberta." Kerber and Vinci have not played since 2013, and each player has undergone a transformation since. In 2016 Kerber has won her first major, reached her first Wimbledon final and emerged as a threat to Williams at the top of the rankings. Vinci, who reached the US Open final last year, is now a Top 10 player who knows what it takes to win in New York. It will take an attacking mindset for the 33-year-old Italian to pull off another famous upset. On Sunday Vinci told reporters that she has been dealing with injuries to her left leg and back and said she has barely practiced over the last three days. She will not want to get sucked into a physical encounter against a younger, fitter Kerber. Even with the health issues, Vinci is still a very dangerous player. The four-time US Open quarterfinalist has always thrived in New York. "I don't know why I'm always playing good here," she said after defeating Lesia Tsurenko in straight sets on Sunday. "Maybe the courts, maybe the atmosphere, maybe the crowd. I always play so good here." Will Vinci be able to keep the magic percolating against one of the game's fiercest all-court players on Tuesday? The Italian knows it will be difficult. "Kerber is playing so good," she said. "Almost No.1."
Pick: Kerber in two
She's back! Not many pundits predicted that Caroline Wozniacki would be gunning for a semifinal spot on Day 9 of the US Open, but this is why they play the matches. And the same could be said of Latvia's Anastasija Sevastova, a 26-year-old who entered this year's draw with a 2-3 lifetime record at the US Open. But both unlikely quarterfinalists have marched in lockstep into the second week, carving through the draw with the loss of only one set between them. Two-time runner-up Wozniacki avoided an upset against American Taylor Townsend in the first round, then shocked ninth-seeded Svetlana Kuznetsova in the second round. Since then it's been all systems go for the Dane, and she's hoping to capitalize on this sudden uptick of form to get deeper into the draw. Many are surprised by Wozniacki's run, but the No.74-ranked Dane says she never lost faith in her ability to be a big-impact player. "I'm not surprised that I could make it this far because I always believe in myself and I always believe that when I get on court I'll win the match," she said on Sunday after defeating No.8-seeded Madison Keys in straight sets. "I know that when I play my best I'm tough to beat." How will Sevastova handle the Wozniacki challenge? The Latvian has come through with giant upsets against No.3-seeded Garbiñe Muguruza and No.13-seeded Johanna Konta, and is still coming to grips with the excitement - and fatigue - that comes with success on the Grand Slam stage. "I still cannot believe it," she said. "Mentally I'm spent. Totally spent. But it's amazing, yeah."
Pick: Wozniacki in two
By the Numbers...
2-0 - Wozniacki's record against the Top 10 this season. The Dane defeated No.10 Svetlana Kuznetsova in the second round and No.9 Madison Keys in the round of 16.
16 - Kerber has dropped just 16 games in her first four matches in New York.
4 - Vinci has reached the US Open quarterfinals in four of the last five years.
0 - Number of sets dropped by Kerber and Sevastova in their first four rounds.