The 33-year-old Pennetta won the U.S. Open final 7-6 (4), 6-2 on Saturday, a day after Vinci stunned Serena Williams in the semis. Unlike the top-ranked Williams, Pennetta was unfazed by her former junior doubles partner's slices and volleys, and the 43rd-ranked Vinci couldn't recapture her brilliant play from Friday.
Both players were in their first major final in this unexpected matchup. Vinci is 32, and their combined age was the highest for a Grand Slam women's final in the Open era, which started in 1968.
The previous record for the oldest first-time major champion was another Italian: Francesca Schiavone was nearly 30 when she won the 2010 French Open, inspiring her two countrywomen.
Pennetta has also announced that she will retire from tennis.