The second round of the bett1open saw Victoria Azarenka face a familiar foe, and come away with a familiar result. For the 10th time in 11 matches, the No.7 seed defeated Angelique Kerber, coming from 1-4 down in the second set to progress 6-3, 7-5.

The result puts Azarenka into her first grass-court quarterfinal since Wimbledon 2015. Aggression off the ground and on return was key for the Belarusian, who struck 28 winners to Kerber's 16, and who needed to overcome a spate of six double faults in the second set.

The pair first played in the 2012 Indian Wells semifinals, but only once previously on grass - Azarenka's 6-4, 7-5 victory in the 2012 London Olympic Games quarterfinals. Only three matches in their series have gone to three sets, and Kerber has only won once - in the 2016 Australian Open quarterfinals, en route to her first Grand Slam title.

Neither of those patterns changed in Berlin. A high-quality first set was decided by narrow margins. Azarenka saved both of the break points she faced in the opening game, and leading 4-3 brought up a first on the Kerber serve thanks to a delicate dropshot. The German responded with a double fault, and Azarenka served out the set efficiently.

Having committed a meagre four unforced errors in the first set, Azarenka became somewhat more generous in the second in tallying 15 - as well as at least one double fault in each of her first five service games. Kerber took full advantage, breaking for 3-1 with a spectacular pass and then again for 5-3 with a backhand winner down the line.

Azarenka gets 10th win over Kerber for first grass QF since 2015: Berlin Highlights

2021 Berlin

But Azarenka never let momentum get away from her, breaking Kerber back both times with strong return games. After finding three clean winners to prevent the three-time Grand Slam champion from serving out the second set, Azarenka took control again to race through the last four games in a row. Serving it out, she needed four match points, but sealed her last-eight spot as Kerber sent a backhand long.

"I always really enjoy our battles," Azarenka said. "I always know that it's going to be a battle, no matter what and I prepare myself for that - there is a certain preparation and motivation going into matches like that.

"[In the second set] I feel like I was coming back to what was working for me - some of the points I was falling off and not playing aggressive. Once I knew that I was stepping up a bit more consistently."

Azarenka will next face Jessica Pegula, who also extended a dominant head-to-head to reach her first career quarterfinal on grass. The American dispatched No.4 seed Karolina Pliskova 7-5, 6-2 in just one hour and 15 minutes - her fourth win over the former World No.1 in as many meetings this season.

Pliskova committed 28 unforced errors, including a drive volley that sailed over the baseline down set point in the first set and a wild forehand facing her first match point.

Muguruza delivers big-point masterclass

A third multiple Grand Slam champion in action, No.6 seed Garbiñe Muguruza, also progressed in straight sets, 6-4, 6-3 over Elena Rybakina. The scoreline belies how narrowly contested the battle was, though.

Rybakina, fresh off a maiden major quarterfinal run at Roland Garros, delivered plenty of highlights and struck 35 winners to 20 unforced errors - and Muguruza required all of her experience to withstand the barrage. Key for the Spaniard was her instinct for raising her game on big points, saving six of the seven break points she faced and converting four of the five she held on Rybakina's serve.

Having taken control to lead 4-2 in the first set, a flurry of unplayable forehands from Rybakina pegged her back to 4-4. But Muguruza responded with a brilliant lob, then retained her focus after a crowd-affected delay in play to close out the set.

The quality of the tennis rose to spectacular heights in the second set, which saw five knife-edge games go to deuce. It was emblematic of Muguruza's match that she won every one of those five, including saving all six break points she faced - the majority with clutch serves.

By contrast, Rybakina was unable to translate breathtaking shotmaking into scoreboard reward. The Kazakh, who was celebrating her 22nd birthday, fought valiantly with all the tools in her increasingly wide repertoire. The final two games of the match were mini-thrillers of their own: Rybakina came up with fine dropshots, bold drive volleys while moving backwards and searing winners on the lines.

But it was Muguruza who held firm to win the two consecutive five-deuce marathons, sealing her second match point - and a quarterfinal date with Alizé Cornet - with a heavy backhand return.

Muguruza resists Rybakina barrage to reach Berlin QF: Highlights

2021 Berlin

Samsonova serves past Kudermetova, seals Top 100 milestone

Earlier, qualifier Liudmila Samsonova scored a long-awaited milestone after upsetting Veronika Kudermetova 6-4, 6-3 in an all-Russian clash. Samsonova first cracked the Top 130 in July 2019, and has largely remained in that echelon ever since. But only now is the World No.106 guaranteed to make her Top 100 debut in next week's rankings.

Samsonova has achieved that in style after pulling off consecutive Top 50 upsets in Berlin to reach her second WTA quarterfinal, and first at 500 level. Against Kudermetova, she was impregnable on serve: the 22-year-old did not face a break point, and dropped just 11 points behind her delivery in total.

She was also sharp in taking advantage of the rare opportunities she had on her compatriot's serve, converting two of the three games in which she held break point - including a ferocious forehand return winner to seal the first set.

Samsonova reaches first 500 QF, breaks Top 100 with Kudermetova win: Berlin Highlights

2021 Berlin