New Delhi, Oct. 22 -- World number one Elena Rybakina moved into the quarterfinals of the Ningbo Open on Thursday in her first match back from a foot injury. The top seed and defending champion was leading 5-0 when Polina Kudermetova retired.

Elena Rybakina, the Moscow-born Kazakh, looked sharp from the start on the hard courts in eastern China. Polina Kudermetova, ranked 105 in the world, was unable to continue and called time on the match because of an injury of her own. The retirement handed Rybakina a place in the last eight without having to complete the set. For a player coming back from a recent absence, the short outing provides useful match time while protecting her from a longer physical battle.

Rybakina, 27, claimed the US Op...