Angelique Kerber reached her second US Open semi-final on Tuesday with a 7-5, 6-0 victory over 2015 runner-up Roberta Vinci which also edged her closer to the world number one spot.

The German second seed showed remarkable powers of resilience to retrieve three breaks of serve against the Italian 33-year-old in the first set.

She will face either two-time runner-up Caroline Wozniacki or shock quarter-finalist Anastasija Sevastova of Latvia for a place in Saturday's championship match.

In a powerful demonstration of her title credentials, 28-year-old Australian Open champion Kerber wrapped up the second set by allowing Vinci just five points on her serve.

"It's always tough to play Roberta, she always comes out to play great tennis," said Kerber, who last made the semi-finals in New York in 2011.

"I am happy to win in two sets which means a lot to me."

Kerber could dethrone Serena Williams, who she has already faced in the Australian Open and Wimbledon finals this year, on top of the world rankings if results go her way.

But she insists she is not looking that far ahead.

"I try to stay in the moment, be positive and go match by match," said the world number two.

Vinci, bothered by a foot injury this tournament and playing with her left calf strapped on Tuesday, was ahead with a break on three occasions in the opening set for leads of 1-0, 3-2 and 5-4.

But Kerber kept reining her in and with the seventh break in 12 games, the German took the opener after 54 minutes when Vinci was called for a foot fault.

The Italian aimed sarcastic applause and a thumbs-up at the impassive line judge, but the veteran never regained her composure as she garnered just 10 points in a 24-minute second set.

Later Tuesday, Wozniacki will aim to make a Grand Slam semi-final for the first time since going all the way to the final of the US Open two years ago.

Wozniacki, a former world number one and runner-up in 2009 and 2014, has already put out top ten seeds Svetlana Kuznetsova and Madison Keys on her way to the quarter-finals.

Now ranked 74, the popular Dane faces unlikely quarter-finalist Sevastova, who was so depressed about the state of her game back in 2013 that she retired.

Her decision to return in 2015 has been richly rewarded with a shock victory over French Open champion Garbine Muguruza in the second round.

The remaining quarter-finals take place on Wednesday with world number one Williams facing fifth seed Simona Halep of Romania and Croatian teenager Ana Konjuh facing fellow big-hitter, Karolina Pliskova of the Czech Republic.