CINCINNATI–Iga Swiatek moved into the semi-finals of the Cincinnati Open as Elena Rybakina was forced to retire with a heel injury less than half an hour into their clash Thursday. Elena Rybakina's Cincinnati withdrawal raises concerns over the fitness of the world number two ahead of US Open. Key points and original sources are listed below.

• CINCINNATI–Iga Swiatek moved into the semi-finals of the Cincinnati Open as Elena Rybakina was forced to retire with a heel injury less than half an hour into their clash Thursday. Rybakina’s withdrawal raised concerns over the fitness of the world number two...S1

• Elena Rybakina's Cincinnati withdrawal raises concerns over the fitness of the world number two ahead of US Open.S2

• Two-time Grand Slam champion Elena Rybakina retired injured from her Cincinnati Open quarter-final against Iga Swiatek on Thursday, ending her chance of taking over as world number one. Rybakina retired with an ankle problem while trailing Swiatek 4-1.S3

• Elena Rybakina was forced to retire from her quarter-final against Iga Swiatek at the Cincinnati Open due to an ankle injury.S4S5

• Iga Swiatek moved into the semi-finals of the ATP-WTA Cincinnati Masters as Elena Rybakina was forced to retire with a heel injury less than half an hour into their clash Thursday.S6

• Elena Rybakina was forced to retire with a heel injuryS7