Germany's Andrea Petkovic sobbed during a changeover but set up a second round clash against Jelena Jankovic after battling past Austrian qualifier Tamira Paszek 3-6, 6-2, 6-2 in Stuttgart on Tuesday.
Serbia's former world number one Jankovic found no resistance from Spaniard Beatriz Garcia Vidagany, easing through in the claycourt tournament with a 6-1 6-2 victory.
Paszek, 20 and ranked 88th, showed no signs of nerves, punishing local favourite Petkovic with a series of bludgeoning forehands to claim the first set with her stunned opponent double-faulting on set point and then sobbing.
Petkovic, the world number 19 who was a quarter-finalist at Janauary's Australian Open, took the initiative early in the second set with more aggressive play but Paszek looked to have found a way back into the match taking a 2-0 lead in the third.
However, the 23-year-old roared back with a series of stinging baseline shots to win the next six games, firing a forehand down the line on her first matchpoint after two hours and 17 minutes.
"I was tired and needed a bit of time to get started, just like a diesel engine," the German number one, who helped her nation beat the United States in the Fed Cup at the weekend, said in a courtside interview.
"I felt the crowd giving me a boost because maybe I was a bit too comfortable after the weekend (win)," she added.
Fellow Germans Sabine Lisicki and Julia Goerges joined her in the next round, albeit with far less trouble.
Lisicki looked to be back to her best after an injury-hit 2010, firing 14 aces past Slovakian Dominika Cibulkova to win 7-5, 7-6.
Cibulkova managed to force a second set tiebreak but Lisicki fought back, winning six straight points to clinch the match and set up a second round clash with world number six Li Na of China, runner-up at this year's Australian Open.
Goerges also advanced with a 6-3, 6-1 win over Dutchwoman Michaella Krajicek and will meet fourth seed Victoria Azarenka.
Australian Samantha Stosur, out to defend a bagful of points earned during her fine 2010 claycourt season that culminated with a French Open final, eased past Spaniard Maria Jose Martinez Sanchez 7-5, 6-1.
Russian Anna Chakvetadze retired for the third straight tournament, this time against Slovakian Zuzana Kucova after collapsing in the third set.
World number one Caroline Wozniacki is in action on Wednesday against Kucova.