Agnieszka Radwanska's place at next week's US Open has been cast into doubt due to concerns over her fitness.
The world number two was forced to retire from her second-round clash with Olga Govortsova at the New Haven Open yesterday after struggling with a shoulder problem.
Radwanska, who had received a bye in round one, was trailing the Belarusian 6-0 2-1 when the match was abandoned.
The first-round singles matches at Flushing Meadows are scheduled to begin on Monday morning.
