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