IT was truly a family affair in the second round of the Korea Open in Seoul, with sisters Polina and Veronika Kudermetova both causing upsets against fellow Russian opponents to stamp their ticket into the quarter finals.

The older of the sisters, Veronika, who is a former Top 10 player and now ranked 27th in the world, upstaged second seed Liudmila Samsonova in a straight sets victory. Kudermetova won 6-4 6-2, giving her opponent no chance to come back like she did to Maria Camila Osorio Serrano a week ago when 5-0 up in the deciding set.

The victory improved the older Kudermetova sibling’s record to 5-2 against Samsonova, getting the job done in an hour and 40 minutes. She won71 per cent of her first serve points off a 47 per cent clip, but recovered well to break even off her second serve. Samsonova struggled more (second serve percentage of 33) and Kudermetova broke five times to two thoughout the course of the match.

“It’s really nice feeling because this season, let’s say, is not perfect for me,” Kudermetova said.

Siblings can often be a great help on Tour, and after Polina lost in qualifying to Chinese ninth seed Jia-Jing Lu, it was Veronika who reminded her to sign up as a lucky loser as her 21-year-old sister was the highest ranked loset in the second round of qualifying.

That advice came with the knowledge that Polish player Magdalena Frech – coming off a title in Guadalajara – would likely withdraw, which is exactly what happened. Poliina gained the lucky loser spot and ground out a 7-5 6-4 win over Priscilla Hon and then overnight upset seventh seed Ekaterina Alexandrova.

“We’re together practising all the time,” Polina said. “It was a really good experience for me, because she was No.8 in the world and I’m only going up, up now. All the time I’m learning.”

In her win over Alexandrova, Kudermetova raced to a 6-2 lead then had to battle hard in the second set before closing it out 6-2 7-5 in 97 minutes. She served five aces and won 71 and 50 per cent of her first and second serves, while converting six break points from 11 chances in the victory.

As the draw stands, the Kudermetova sisters could meet in the semi-finals, albeit with a couple of tough matches coming up in the quarters. Polina will likely take on Brazilian third seed Beatriz Haddad Maia providing she wins against Aussie Ajla Tomljanovic, while Veronika faces one of Amanda Anisimova or Viktoriya Tomova.

In the other two Round of 16 matches completed overnight, Ukrainian talent Marta Kostyuk wasted no time dispatching of British qualifier Heather Watson in 75 minutes, 6-2 6-2, while another young Russian in Diana Shnaider stamped her place into the quarter finals with a 6-3 6-3 67-minute win over Canadian qualifier, Carol Zhao.