The German beat Vinci 7-5 6-0 in Arthur Ashe Stadium.
Kerber will snatch top spot away from Serena Williams if she equals or betters the American’s performance at Flushing Meadows and she turned up the heat with another ruthless victory.
Serena Williams faces Simona Halep later tonight.
In the men’s singles last night, Gael Monfils saw off Lucas Pouille in an all-French clash at Flushing Meadows, advancing to the semi-finals 6-4, 6-3, 6-3.
Meanwhile Andy Murray has been struggling to sleep at the US Open, but insists his mind has been refreshed by his demolition of Grigor Dimitrov.
Murray produced a flawless display against the Bulgarian to win 6-1 6-2 6-2 and today faces Japan’s Kei Nishikori at Flushing Meadows for a place in the semi-finals (6.30pm Irish time).
The British number one had been out of sorts in the previous round, when he had to battle past Italy’s Paolo Lorenzi, and it seemed fatigue might finally be catching up with him at the last grand slam of the season. Dimitrov, however, ran into one of Murray’s best performances of the year and the Scot believes he is now back on track ahead of the quarter-finals.
“I’ve not been sleeping great since I’ve been here. I don’t know why,” Murray said.
“On Sunday night I tried to get in bed early and I slept for 12 hours straight. I never do that. I never sleep that long. I went to bed very early.
“My best tennis is in there. Not every day do you play your best. When you don’t play your best and win, it’s a really positive thing.
“A lot of people worry about that or panic, like, ‘This is terrible’. But you played one bad match. I won. I’m still in the tournament. I was able to play great tennis against Grigor.”
Murray has reached the final at seven consecutive tournaments. He is set for a more testing encounter against Nishikori, a US Open runner-up two years ago, has won only one of their eight previous meetings and he was beaten 6-1 6-4 when they met at the Olympics last month.