Oeiras - China's Peng Shuai used a minimal amount of clay court preparation on Tuesday to knock French top seed Marion Bartoli out in the first round of the Portugal Open 6-0, 1-6, 6-4.
Peng, a 2010 semi-finalist in her only previous appearance at the event, had just limited time to train after returning to her homeland to treat a shoulder injury following a Miami second-round loss in March.
After receiving treatment in her hometown of Tianjin, she travelled on to Germany where her meagre clay preparation proved just the ticket to stunning Bartoli, the world number 14 who has now lost her last four WTA matches dating to mid-March.
"I"m very happy to win in such windy conditions," said the 27-year-old Peng, ranked 34th and second Chinese behind Li Na. "The clay was blowing around a lot, making it even more difficult."
Pen won in an hour and three-quarters as the erratic Bartoli produced eight double-faults and lost serve five times.
The quirky French player has reunited with her doctor father Walter as coach after several months of unsuccessful trials with other potential mentors including former Wimbledon champion Jana Novotna, but is still looking for a win.
"The first match on clay is always tough for me," said Bartoli. "I had a lot of trouble finding my game and my feet on the court.
"She was playing extremely well. I just tried my hardest and was able to play some good shots in the second set. I felt like the third was really close.
"We both started to play quite well, but at 3-3 when I had 40-15 she hit quite a lucky return and that really hurt me.
"It was a very difficult draw, but I think it is better for me to have those kind of matches early in the clay court season and try to improve for the big events coming up."
Elsewhere in the opening round, Galina Voskoboeva of Kazakhstan beat Swede Sofia Arvidsson 6-3, 6-4 to next face two-time grand slam winner and wild card entry Svetlana Kuznetsova.
Wimbledon quarter-finalist Tamira Paszek has now gone winless for three months since the Australian Open, with the 31st-ranked Austrian losing her seventh straight match as she went down 6-1, 6-3 to Romanian Monica Niculescu.
In the men's draw, France's Julien Benneteau joined Bartoli at the exits as the fifth seed went down to Spanish qualifier Pablo Carreno-Busta 6-3, 6-4.
Spaniard Albert Ramos will line up in the second round against number two seed Stanislas Wawrinka thanks to a defeat of Argentine Carlos Berlocq 7-6 (7/4), 2-6, 6-3. Alejandro Falla of Colombia defeated Russian Alex Kuznetsov 7-5, 6-4.
Spain's David Ferrer heads the seeding but will not start until the second round after bye handed to the top four men in the field.
Results on the second day of the WTA/ATP Portugal Open on Tuesday (x denotes seeding):
Galina Voskoboeva (KAZ) bt Sofia Arvidsson (SWE) 6-3, 6-4
Monica Niculescu (ROM) bt Tamira Paszek (AUT) 6-1, 6-3
Peng Shuai (CHN) bt Marion Bartoli (FRA x1) 6-0, 1-6, 6-4
Romina Oprandi (SUI) bt Kiki Bertens (NED) 6-3, 6-3
Kaia Kanepi (EST) bt Kristina Mladenovic (FRA) 6-4, 6-3
Anastasia Pavlyuchenkova (RUS x3) bt Shahar Peer (ISR) 6-4, 6-4
Estrella Cabeza Candela (ESP) bt Aravane Rezai (FRA) 5-7, 6-1, 6-3
Francesca Schiavone (ITA) bt Lourdes Dominguez Lino (ESP) 6-2, 4-6, 6-3
Monica Puig (PUR) bt Julia Goerges (GER x8) 7-6 (7/3), 6-2
Ursula Radwanska (POL) bt Dominika Cibulkova (SVK x2) 2-6, 6-4, 6-4
Pablo Carreno-Busta (ESP) bt Julien Benneteau (FRA x5) 6-3, 6-4
Alejandro Falla (COL) bt Andrey Kuznetsov (RUS) 7-5, 6-4
Albert Ramos (ESP) bt Carlos Berlocq (ARG) 7-6 (7/4), 2-6, 6-3
Victor Hanescu (ROM) bt Rui Machado (POR) 6-4, 6-4
Paolo Lorenzi (ITA) bt Niels Desein (BEL) 6-3, 4-6, 6-2
Robin Haase (NED) bt Pablo Andujar (ESP) 4-6, 6-2, 6-3
Tommy Robredo (ESP x8) bt Daniel Gimeno-Traver (ESP) 2-6, 7-5, 6-3
Gastao Elias (POR) bt Horacio Zeballos (ARG x7) 6-3, 6-4