NURNBERG, Germany - Anna-Lena Friedsam's comeback to professional tennis continued to gain steam on home soil on Wednesday at the Nürnberger Versicherungscup.

The wildcard, currently ranked World No.523 after recently returning from shoulder surgery, upset No.8 seed Andrea Petkovic to reach the quarterfinals, 6-3, 6-1.

The 25-year-old German has been injury-plagued since reaching the second week of the Australian Open and a career-high ranking of World No.45 in 2016, including missing over a year between last year's Australian Open and her return to professional tennis this February.

Nonetheless, she showed the kind of tennis she is capable of producing to qualify at the Premier-level Porsche Tennis Grand Prix in April, also giving Kiki Bertens a tough match in the first round and winning the doubles title.

She continued to show her form on home soil to upset her eighth-seeded compatriot in under an hour on Wednesday.

"That was a very good match from me," Friedsam said. "It was tight at the beginning of the first set, we played really good, but I was able to put the next level on, and the match went on my side then."

Friedsam served seven aces and saved all four break points she faced, allowing Petkovic to win just three points against her serve in the second set.

"My serve was very, very good today. I was happy about how I served," she added.

"I had a good feeling on the directions, and that was a key point for today's match."

The younger German held on from a 0-40 deficit in the opening game of the encounter, in which she ultimately saves all of the break points she faced for the match, and secured the deciding cruical break to love in the eighth game of the first set.

She continued to roll into the second, running her games won streak to six as she built a 4-0 lead, with Petkovic needing to save two break points just to get herself on the board, and ultimately save the bagel. 

Friedsam advances to face top seed Yulia Putintseva, who ousted another German in Mona Barthel in her second-round match.

"I'm really looking forward to this match. She's a great player with a lot of intensity," the German assessed.

"We had a couple of matches in the juniors and it was always very tough. I like how she plays, I like the tension, so I'm looking forward to it."