No.2 seed Garbiñe Muguruza survived a stern challenge from Czech Tereza Martincova to debut at the VTB Kremlin Cup with a victory.

Muguruza's 6-4, 4-6, 6-3 second-round victory lasted 2 hours and 45 minutes and earned her a seventh quarterfinal berth of the season.

The lone Spanish woman in the singles draw in Moscow this week, Muguruza is looking to match the achievement of her coach, Conchita Martinez, who won the title in the Russian capital back in 1996. 

Comeback secured: After losing in her opening match following a first-round bye at Indian Wells, the World No.5 managed to avoid a repeat in Moscow.

Winning five straight games to take the first set from a 4-1 deficit, Muguruza also denied Martincova three chances to lead 5-2 as she served at 4-2, 40-0.

The Czech, in the midst of a breakthrough season where she's shaved nearly 70 places off her ranking, was bidding for the first Top 10 win of her career (now 0-4), and forced a final set from a set and a break down (6-4, 3-2). 

After the pair traded breaks to begin the final set, Muguruza lost just two points in her three ensuing service games to finish off the win.

Words from the winner: "I feel happy. It's a first victory of my in Russia and I'm very excited. It was a very difficult match, and I'm happy to get it," Muguruza said.

"I think I served well in the third set and I kept attacking and doing my game. I got the break and I managed to hold it until the end."

Muguruza hit 35 winners in victory, 11 more than Martincova, and three less unforced errors (39 to 42). In total, the two players combined for 12 breaks of serve on 32 break point chances, with the Spaniard breaking eight times. 

Up next: In the last eight, Muguruza will face either No.9 seed Anett Kontaveit or Germany's Andrea Petkovic. 

Fellow debutant Sabalenka makes winning return to competition

Forced out of the BNP Paribas Open due to a positive COVID-19 test in Indian Wells, Aryna Sabalenka got back on the winning track on Wednesday. The top seed, a wildcard into the WTA 500 event, edged Ajla Tomljanovic in three sets, 7-6(2), 4-6, 6-1, to book her own place in the last eight. 

Photo by VTB Kremlin Cup

Like Muguruza, Sabalenka is also making her main-draw debut in Moscow this week. Five years ago, when she was 18 years old and ranked World No.164, she lost in the first round of qualifying. 

"For sure, I'm happy to be here. It really feels great [to be] in Moscow. It's a great atmosphere and really cool," Sabalenka said after the match. "It was quite a tough opponent for my first match after a break. Step by step, I found my range and I was feeling comfortable on the court. Hopefully, I can play even better in the next match."

Stats of the match: Sabalenka hammered 47 winners and 10 aces in victory, breaking Tomljanovic's serve five times in 11 chances. Unable to seal the first set despite leading 5-3, Sabalenka bounced back in the tiebreak and won five of the first six points to eventually wrap up a lead in just short of an hour. 

Tomljanovic rallied to force a decider after trailing 2-0 in the second set and won three straight games to take her first lead of the contest. In the five ensuing service games, the return won just two points - both of which came in Tomljanovic's hold to 30 at 2-2 - before the Aussie broke to 15 to send the match the distance. 

Her momentum was quickly quelled, though, despite holding serve to begin the third set after saving a break point. Sabalenka won six straight games to win the match, and never faced break point herself in that time.

A good omen? Sabalenka improved her head-to-head against Tomljanovic to 4-1 with the victory. Their last meeting came in Abu Dhabi in January, where Sabalenka's 7-5, 6-4 victory was the first step on her way to the title.

For a spot in the semifinals, she'll face home favorite Ekaterina Alexandrova, who defeated Ukraine's Anhelina Kalinina, 6-4, 6-1, and was a quarterfinalist at the last edition of the VTB Kremlin Cup two years ago. The two have split two prior meetings, both of which came at the season-opening Shenzhen Open in 2017 and 2019.

Former Moscow champion Anastasia Pavlyuchenkova joined Alexandrova as a Russian winner on Day 3 in Moscow. No.4 seed Pavlyuchenkova prevailed in the extra-late nightcap, defeating American qualifier Bernarda Pera, 6-2, 7-5, in an hour and 40 minutes.

Pavlyuchenkova, currently the top-ranked Russian at World No.16, needed five match points spread over the final four games before claiming a quarterfinal spot after 1:00 a.m. local time. Pavlyuchenkova has reached the Kremlin Cup final three times, winning the title in 2014.