Moved from the Arthur Ashe Stadium court to Louis Armstrong to bring Federer’s match forward, Wawrinka appeared untroubled by the change of venue, needing just an hour and 47 minutes to repel big-hitting South African Kevin Anderson 6-4 6-4 6-0.
Second seed Federer turned in an equally economical effort, brushing aside Frenchman Richard Gasquet 6-3 6-3 6-1 in a tidy 87 minutes to set up an all-Swiss semi-final on Friday.
The other side of the draw features a battle of the big men, with top seed Novak Djokovic taking on defending champion Marin Cilic.
“Emotionally it’s not so hard for me,” said Federer, who holds a commanding 16-3 advantage over his Davis Cup team mate and reigning French Open champion.
“But subconsciously, you know he knows what your preferences are, where you like to go and where you’re probably going to go,” he added
“That’s the weird part. I feel we meet each other somewhere in our minds before the point is being played out.”
Federer and Gasquet are both armed with elegant one-handed backhands but apart from that aesthetically pleasing stroke, there were very few similarities in their lopsided contest.
The 17-time grand slam winner could hardly miss and Gasquet all too often played the role of innocent bystander as the Swiss maestro uncorked 50 winners to a mere eight from the 12th seeded Frenchman.
Anderson, meanwhile, lacked the energy he displayed in a fourth round upset of third seed Andy Murray, allowing Wawrinka to dictate play for large stretches of the match.
The South African, who leans heavily on his serve, could manage just nine aces and one break point the entire match, which he was unable to convert.
“I’ve improved a lot over the past three years and feel much closer to his level now,” Wawrinka said of his compatriot.
“He is playing really well here so I will need to be at my best. He’s had some amazing matches and I know it will be a big challenge but I think I’m ready.”
Halep moved closer to a first grand slam singles title after edging Victoria Azarenka 6-3 4-6 6-4 to set up a meeting with Flavia Pennetta, who toppled Czech fifth seed Petra Kvitova 4-6 6-4 6-2 to join compatriot Roberta Vinci in the last four.
Defying the odds, rankings and age, 33-year-old Pennetta and 32-year-old Vinci etched their names in history by becoming the first two Italian women to reach the semi-finals of the same grand slam in the Open Era.
With 33-year-old Serena Williams also in the last four, 23-year-old Halep will be conceding almost a decade of experience to her remaining challengers.
“Of course we are a little bit old for the age of tennis right now,” Pennetta admitted. “But we are here and still fighting.”
However, the dream of an All-Italian final will require some special magic, particularly from Vinci, who has the daunting task of facing three-times defending U.S. Open champion and world number one Williams.
(Editing by John O’Brien)