However, the Pennetta backhand put paid to that and the Briton would not get another chance.
Denmark's Wozniacki eventually outmuscled Pennetta in three hours despite the Italian hitting more than twice the number of winners.
Pennetta's 16th-seeded compatriot Francesca Schiavone was dumped out by veteran American qualifier Jill Craybas, who won 7-6 (9-7) 6-2.
Italy can reach their third final in four years on Sunday when Pennetta faces Kuznetsova and Schiavone meets Chakvetadze.
The 23-year-old was in control after winning the first two matches, and now has a 7-0 career record over Pennetta.
The French 17th seed, herself another former No. 1, won 7-5 6-3 against 15th-seeded Italian Flavia Pennetta earlier on Saturday.
Flavia Pennetta and Francesca Schiavone claimed singles wins over Anna Chakvetadze and Svetlana Kuznetsova in Castellaneta Marina in southern Italy.
Peer was joined by third seed Yanina Wickmayer of Belgium, and Italian duo Francesca Schiavone and top seed Flavia Pennetta.
Pennetta was increasingly dominant behind her first serve and, despite making her work, Keothavong could not keep the Italian at bay.
Italian 14th seed Flavia Pennetta defeated Romania's Sorona Cirstea 6-1 1-6 6-1 to earn a second-round clash with German Andrea Petkovic.
Swiss player Schynder dropped the opening set against Flavia Pennetta of Italy but came back strongly to win 4-6 6-0 6-1.
The winner of that match will play either fifth seed Petrova or last year's losing finalist, 10th seed Flavia Pennetta of Italy.
Pennetta defeated Anna Chakvetadze, a late replacement for Vera Zvonareva, who pulled out on Friday because of an ankle injury, 6-4 6-0.
The Italians, led by 2010 French Open champion Francesca Schiavore and world No.22 Flavia Pennetta have won four of their last seven meetings.
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But their compatriot Flavia Pennetta made a shock early exit as the 19th seed lost 6-3 1-6 6-2 against Russian qualifier Nina Bratchikova.
Pennetta beat Lucie Hradecka in straight sets on Saturday -- and followed up that performance with a hard-fought 6-4 7-5 success over Petra Kvitova.
Seventh-ranked Elena Dementieva will take the American's place as top seed, with Italian No. 12 Flavia Pennetta second and Yanina Wickmayer of Belgium third.
The second seed will now play Italian Flavia Pennetta for a place in the quarterfinals after she beat seventh seed Vera Zvonareva of Russia.
Pennetta, 28, took the initiative with an immediate break, consolidated by a backhand arrowed down the line which would become a feature of the match.
Keothavong battled hard but Pennetta, a winner of nine WTA Tour titles and recent top-10 player, was able to exert more pressure when it mattered.
Hungary's Agnes Szavay progressed to the second round after Italian fourth seed Flavia Pennetta was unable to complete their match despite winning the first set.
Pennetta came through 6-2 6-2 in one hour and four minutes and goes on to face fellow Italian Roberta Vinci or France's Virginie Razzano in round two.
With a 2-0 lead overnight, world No. 11 Flavia Pennetta's 7-5 6-2 victory over Melanie Oudin in Sunday's opening singles match gave the Italians an unassailable lead.
The final takes place on 7-8 November in Reggio Calabria, Italy, and the hosts will be represented by Flavia Pennetta, Francesca Schiavone, Roberta Vinci and Sara Errani.
It was always likely to be a tall order as Keothavong's only win over the Italian had come 10 years ago, Pennetta winning their other meeting back in 2002.
After Italy claimed both singles rubbers on Saturday, world No.15 Flavia Pennetta won her second match on Sunday to ensure her nation will contest November's climax to the tournament.
Following Pennetta's victory, Sara Errani stepped in for Schiavone to beat Hradecka 6-4 6-2 in the final singles rubber, giving Italy a 4-0 advantage with only the doubles remaining.
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