Reigning US Open champion Emma Raducanu is still rolling at the Mutua Madrid Open. The No.9 seed moved safely through to the last 16 in the Spanish capital with a 6-2, 6-1 win over Ukrainian Marta Kostyuk on Sunday, her fifth win in her first seven tour-level matches on clay. 

Having won back-to-back matches just once in the six months following her US Open triumph last summer, Raducanu has now done so twice in as many weeks this clay-court season. 

"I'm definitely very happy with my performance today. Marta is a great opponent ... and I knew it was always going to be a really tough battle. I went out there trying to be really aggressive, and it definitely paid off," Raducanu said after the match. 

"It's my first clay-court season and I'm really enjoying it. Madrid is such a cool city and it's got such a great vibe about it, so I definitely want to try and stay here for as long as possible."

Madrid: Raducanu takes revenge on Kostyuk to reach R3

The pair, just five months apart in age, met for the first time as professionals just six months ago in the quarterfinals of the Transylvania Open. Kostyuk was victorious that day with the loss of just three games, but Raducanu flipped the script for an identical scoreline in her favor in their first clay-court meeting.

Match management: After winning 11 of the last 12 games in her first-round victory of Tereza Martincova, Raducanu's momentum continued against Kostyuk.

Raducanu lost just two points on serve in the opening set, and won seven straight games in the middle of the match to fully take command. She also hit just one unforced error in the match's first 12 games—racking up just five in all—never faced break point in victory, and hit 14 winners.

Up next: Another Ukrainian player awaits Raducanu next in the form of Anhelina Kalinina, who lost just three games in upsetting Garbiñe Muguruza.

Kalinina upsets Muguruza in Madrid for first Top 10 win; Andreescu routs Collins

Teichmann upsets Fernandez in all-lefty Round 2

Two left-handers arrived, and only one could advance: in 90 minutes, Jil Teichman knocked out No.17 seed Leylah Fernandez to reach Round 3. 

The 6-4, 6-4 win was Teichmann's third over a Top 20 player this season, and first on clay since she beat then-World No.5 Elina Svitolina in the first round of Madrid a year ago. She'll next face No.16 seed Elena Rybakina, who moved through to the last 16 after Katerina Siniakova retired from their match after playing seven games. 

Rybakina was leading 6-0, 1-0 when Siniakova proved unable to continue due to an abdominal injury.