In the final, she faced home favorite and No. 1 seed Marion Bartoli and won the title after Bartoli retired early in the second set. After that performance, Petkovic reached her new career-high ranking of No. 12 as of 23 May 2011. As the 15th seed, Petkovic reached the quarterfinals of the French Open. She beat Bojana Jovanovski, Lucie Hradecká, 24th seed Jarmila Gajdošová, and 25th seed Maria Kirilenko to reach the last eight, where she lost to seventh seed Maria Sharapova. One month later, Petkovic lost in the third round at Wimbledon against the young Russian player Ksenia Pervak. In August, coach Dušan Vemić joined the team. Petkovic she became the sixth German player in history to crack the top 10 by winning her opening match at the Mercury Insurance Open in San Diego against American player Alexa Glatch. At the Rogers Cup in Toronto, Canada, she made it to the quarterfinals where she lost to Agnieszka Radwańska. At Cincinnati, Petkovic made the semifinals in spite of injury, before losing to Jelena Janković in straight sets. At the US Open, Petkovic was seeded tenth. She beat Ekaterina Bychkova and Zheng Jie to progress to the third round, where she beat the 18th seed Roberta Vinci to set up a fourth-round match with Carla Suárez Navarro, equalling her career best performance at the event up to that point. She went on to win the match against Navarro to secure her first ever quarterfinals spot at the US Open against the world No. 1, Caroline Wozniacki. She performed her trademark dance to delight the audience after her fourth round win. On 8 September she lost to Wozniacki in straight sets. Seeded ninth at the China Open, Petkovic defeated Šafářová and Suárez Navarro to reach the third round where she emerged victorious over Marion Bartoli in three sets. In the quarterfinals, she defeated Anastasia Pavlyuchenkova and proceeded to the semifinals where she won against Monica Niculescu. In the final, she faced Agnieszka Radwańska and lost in a tight three-setter. It was her last match of the year.