Seventh seed Peng was defeated 7-5 6-3 by Sofia Arvidsson as the Swede progressed through to the second round.
The Chinese player was horribly off colour as she failed to find any real rhythm on her serve and was broken at 5-5 in the opening set.
Arvidsson kept her composure and high intensity as she took the second set 6-3 and the Swede now takes on Arantxa Rus in the second round after the Dutch qualifier beat Jie Zheng of China 7-5 3-6 6-4.
Pavlyuchenkova was equally out of form as the ninth seed was dumped out by Chanelle Scheepers of South Africa 7-5 6-2.
Scheepers was inspired as she fired fierce groundstrokes from the back of the court with no hesitation in moving in to put her opponent under pressure.
The first set was tight with Scheepers breaking at 5-5, but the South African thrived in the second, taking it in comprehensive fashion.
Scheepers will next take on Alison van Uytvanck of Belgium in the second round.
Eighth seed Kaia Kanepi fared slightly better as she beat Irina Falconi of the USA 6-3 6-2 in their first-round match.
Kanepi was utterly unerring as she slammed numerous winners and Falconi could not compete at her opponent’s level.
The Estonian will next take on Serbia's Bojana Jovanovski in the second round after she beat Tamaryn Hendler of Belgium 7-5 7-5.
Polish qualifier Urszula Radwanska beat Varvara Lepchenko of the USA 6-2 6-2 to set up a second-round clash with France's Marion Bartoli, who was handed a bye.
Romania's Monica Niculescu beat Indian qualifier Sania Mirza 6-1 7-5 and will face compatriot Simona Halep, after she shocked Jelena Jankovic on Monday.
Finally, Ukraine's Lesia Tsurenko beat Hungary's Greta Arn 6-1 6-4 to set up a tie with Agnieszka Radwanska of Poland.