Angelique Kerber overcame a patchy opening set to move into the US Open semi-finals with what became a comfortable victory over 2015 runner-up Roberta Vinci.
The players exchanged breaks during an inconsistent opener, but it was the German second seed who took control during the second to come away with a 7-5 6-0 win.
Vinci made a promising start as she opened with a break of serve, but she was pegged back in the very next game when Kerber converted her second break point.
And that became a recurring theme, with Vinci breaking her opponent twice more only to immediately cede the advantage.
That profligacy was punished as Kerber finished the set with three game victories in succession - a Vinci double fault wrapping up the set - and she carried that momentum into the second.
The Australian Open champion, who is closing in on Serena Williams' number-one ranking, won 21 of the first 26 points on offer as she raced into a 5-0 lead to leave a tired-looking Vinci hoping for an unlikely collapse.
Despite the Italian showing more resistance as she stared defeat in the face, Kerber eventually put the match to bed with her second match point.
Kerber, who last reached the last four at Flushing Meadows in 2011, will now meet Caroline Wozniacki or Anastasija Sevastova for a place in the final.
Kerber  bt Vinci  7-5 6-0
Kerber - 33/25
Vinci - 17/32
Kerber - 3
Vinci - 1
BREAK POINTS WON
Kerber - 7/11
Vinci - 3/8
FIRST SERVE PERCENTAGE
Kerber - 77
Vinci - 40
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Kerber - 61/29
Vinci - 57/22
Kerber - 74
Vinci - 53