Emma Raducanu was forced to retire from her Korea Open quarter-final against Daria Kasatkina with a foot injury.

Raducanu, who beat Peyton Stearns and Yue Yuan on her way to a last-eight showdown with the top seed, withdrew from the contest after losing the opening set 6-1. 

The 21-year-old was looking to make her second WTA Tour semi-final this year but struggled against the Russian who had beaten her in straight sets in both previous encounters.

Raducanu found herself immediately on the back foot after losing her opening game on serve but got her first point on the board in the third game. 

Kasatkina then took control, racing into a comfortable lead as Raducanu required a medical timeout after the fifth game, having been broken to love. 

Despite a spirited showing in the final game that saw Raducanu handed a break point opportunity, Kasatkina held firm before seeing her British opponent retire. 

The world number 13 will face compatriot Diana Shnaider in the semi-finals, with a potential showpiece match against Beatriz Haddad Maia or Veronika Kudermetova awaiting her.