British number one Johanna Konta withdrew from the final U.S. Open tune-up event in Connecticut with a viral illness, tournament organisers said on Tuesday.
Konta, who beat German Laura Siegemund in the first round of the Connecticut Open, was due to face Spaniard Carla Suarez Navarro on Tuesday in New Haven.
The world number 46 is currently the only British woman with direct entry into the main draw of the Aug. 27-Sept. 9 U.S. Open, where last year she was seeded seventh and suffered a shock defeat in the first round.
Konta, who last year became the first British woman to reach the Wimbledon semi-finals, was enjoying an encouraging North American hardcourt campaign after reaching the quarter-finals in San Jose and round of 16 in Montreal.
Three weeks ago in San Jose, Konta handed 23-time Grand Slam champion Serena Williams the worst defeat of her career in her most impressive win of the season.