The 31-year-old Pennetta's 6-4 6-1 triumph secured her spot in the last four of the year's final Grand Slam against either second seed Victoria Azarenka or Daniela Hantuchova, who are scheduled to playing later on Wednesday.
A US Open record five 30-somethings had reached the last 16, including 30-year-old Vinci, and Pennetta's victory made it at least a trio into the semi-finals.
"I think we just keep playing. Before the career of the woman was shorter, they retired early," Pennetta said about the rise of the 30-somethings at Flushing Meadows.
"It's good to stay physical, in a good way, and play this good tennis at this age. I'm proud of me now."
Hantuchova, 30, of Slovakia is another of the mature set with a chance to advance, while the other semi-final has already been set with defending champion Serena Williams going against fellow 31-year-old Li Na of China.
The good-natured match between the Italian friends who have competed against one another since they were 10 turned into a rout by the second set, which Pennetta raced through in 24 minutes against an error-prone Vinci.
"It was of course a special day for us," said Vinci, who is part of the world number one ranked women's doubles team with fellow Italian Sara Errani, who is still busy defending their US Open double title.
"Is a great chance to go to the semi-final. This time she won, but I think that I'm happy, too, about this tournament."
Following the all-Italian women's quarter-final was a men's last eight showdown between fourth-seeded David Ferrer of Spain and France's Richard Gasquet.
Rounding out the Day 10 schedule at the US National Tennis Center was a quarter-final tilt between second seed Rafa Nadal and his fellow-Spaniard Tommy Robredo, the 19th seed, following the Azarenka-Hantuchova match.
Pennetta, ranked 83rd as she works her way back from a wrist injury that curtailed her 2012 season and made her miss last year's US Open, has continued a strong history of success at Flushing Meadows.
After advancing the quarters in 2008, 2009 and 2011, Pennetta has not dropped a set in her march to the semi-finals, dropping just 25 games in her five victories.
Pennetta had no specific answer to explain her affinity for the US National Tennis Center.
"I don't know. I just enjoy to play here," she said.
Against her Italian Fed Cup team-mate, Pennetta turned a close match into a rout as she induced 28 unforced errors from Vinci, who kept pressing the action without great success, winning just 18 of 34 points she contested at the net.
Their quarter of their draw was something of a festival for the Italians.
In playing Pennetta, Vinci was facing her third successive compatriot, having beaten unseeded Camila Giorgi and Karin Knapp in previous rounds.
Pennetta eliminated fourth seed Errani in the second round.
This marked the sixth year Italy has had a player in the quarter-finals, and second year in a row that two Italians had reached the quarters.
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