British number two Heather Watson has failed to reach the main draw of the Western and Southern Open in Cincinnati.
The 21-year-old was beaten 6-4 6-7 6-3 by New Zealand's Marina Erakovic in a qualifier on Sunday.
Watson had looked to be in control of the match when she moved into a 3-1 lead in the deciding set.
However, Erakovic then reeled off five consecutive games to seal victory after two hours and 32 minutes.
Erakovic, who has partnered Watson in doubles events this season, will face Carla Suarez Navarro in round one.