Mirra Andreeva says facing sister Erika ‘tougher’ than beating top players

Russian teenager Mirra Andreeva has beaten the world's best players to move up to world number seven but on Wednesday she beat a player who had got the better of her for years - her elder sister Erika.

The Andreeva sisters were drawn against each other at the Stuttgart Open but any hopes of a witnessing an absorbing sibling rivalry were put to bed when Erika, 20, was forced to retire with a knee injury while trailing 6-2 1-0.

Mirra had beaten the likes of world number one and two Aryna Sabalenka and Iga Swiatek en route to the Indian Wells title last month, but the 17-year-old said it was tougher to focus when her elder sister is on the other side of the net.

"For me, 75%-80% is about my mental preparation, because you're also not just focusing on yourself and you're not focusing on how to beat her, but you're also focusing (on her) - does she feel good? I don't know," Mirra told reporters.

"I wonder, how does she feel? What are we going to do after the match? How is it going to be? All those thoughts.

"Me, I don't just focus on myself, but I also focus on kind of paying more attention to her. This makes the match more difficult for me... To really just focus on myself, it's almost impossible when I play against her."

The two had met once before in Wuhan last year where Erika - who is now 90 rungs below Mirra in the rankings - triumphed in straight sets.

Mirra Andreeva said she knew Erika was struggling with her knee as they are sharing a room, but also revelled in beating her for the first time - even though the victory did not come under ideal circumstances.

"We played a couple of times on the practices when we were younger, and actually, until Wuhan last year, we never ever played an official match. So we were always playing a couple of games on the practices or a couple of tiebreaks," Mirra said.

"But most of the time, of course she has, like a 90% win (record) against me and this is actually the first time I really won a set against her.

"I just know that, of course, if she would feel her 100%, the score would be completely different and the match would be different as well. But I'm sure that we have a lot of time to play and to show the great level of tennis."

Mirra Andreeva will next play compatriot Ekaterina Alexandrova in the last 16.