Andrea Petkovic assured a German presence in the second round of the bett1open after she upset No.5 seed Garbiñe Muguruza 7-6(8), 6-4 on Tuesday in Berlin.
Former Top 10 player Petkovic took 2 hours and 6 minutes to grab two tough sets against former World No.1 Muguruza. Petkovic is now 4-1 lifetime against Muguruza.
"I really do believe that in these really close matches, the simple and little shift of energy can make the difference," Petkovic said after her home-soil victory. "If you have the crowd on your side, and they are willing you to the win somehow, I think that can really make a difference."
59th-ranked Petkovic had been 0-9 against Top 20 players on grass before her latest win over Muguruza. It is also Petkovic's first win over a Top 10 player since she beat then-No.6 Petra Kvitova at the 2019 US Open.
On Tuesday, Muguruza came back from an early break down to reach a first-set tiebreak, where she held two set points at 6-4. But a double fault and two missed returns gave Petkovic the first of her three set points, and the German eventually eked out the set with a drop shot winner.
Petkovic broke Muguruza with a winning putaway in the first game of the second set, and the German saved four break points while consolidating for 2-0. Muguruza erased four match points at 5-3 with powerful play, but Petkovic served out the match at love in the next game.
Petkovic will next face Aliaksandra Sasnovich for a spot in the quarterfinals. Petkovic won their first meeting easily in 2017, but Sasnovich won the next two in straight sets, including at Rome qualifying last month.
"For me, [Sasnovich is] a very uncomfortable opponent, I've lost to her the last few times," Petkovic said. "Hopefully I will find a better solution this time and change a few things, and just talk through it with my team and be prepared."
Earlier on Tuesday, No.2 seed Maria Sakkari of Greece made swift passage into the second round with a 6-3, 6-2 victory over French qualifier Leolia Jeanjean.
In their only previous meeting, Jeanjean prevailed when they faced off at an ITF Challenger event in 2013, while both were ranked outside the Top 500. But Sakkari, now a Top 10 player, exacted her revenge nine years later with a comprehensive 83-minute win.
Jeanjean had a breakthrough event mere weeks ago when she stunned Top 10 player Karolina Pliskova en route to the third round of Roland Garros, her home Grand Slam, as a wildcard. That result propelled Jeanjean to a new career-high ranking of World No.149.
But Sakkari would not let Jeanjean add another upset to her resume on the grass courts of Berlin. Sakkari won an astounding 92 percent of her first-service points and never faced a break point all day.
Sakkari will meet Australian qualifier Daria Saville in the second round. Sakkari and former Top 20 player Saville have split their two previous meetings, with Sakkari winning their most recent match via retirement at Indian Wells earlier this year.
Last year's Olympic gold medalist Belinda Bencic had to work harder to book her spot in Round 2. No.8 seed Bencic of Switzerland held off German wildcard Jule Niemeier 6-4, 5-7, 6-3 in a rematch of their first-round clash from last year.
Bencic, who was runner-up to Liudmila Samsonova in Berlin last season, converted five of her nine break points on the day, withstanding a barrage of 15 aces from homeland hope Niemeier, who made her Top 100 debut just last month.
The Swiss player eventually prevailed in in 2 hours and 22 minutes, preventing Niemeier from claiming her first Top 20 victory. Bencic will now face another wildcard, Anna Kalinskaya, in the second round. Bencic beat Kalinskaya in the same round in 's-Hertogenbosch last week.