Casey Dellacqua has fallen in the opening round of the combined ATP/WTA event in Cincinnati to Johanna Larsson of Sweden.
She was followed out of the tournament later on Monday by Marinko Matosevic, who went down in straight sets to Spaniard Pablo Andujar.
In a battle between two qualifiers into the main draw, Larsson was superior in every department against Dellacqua.
She won 75 per cent of first serve points and broke serve on five occasions to complete a 6-1 6-3 win in less than an hour.
Dellacqua, meanwhile, struggled on serve, winning only half of her first serve points and just 31 per cent on her second delivery.
Despite the loss, it was an encouraging campaign for Dellacqua in the midwest – she defeated two seeds in straight sets on her path into the main draw, and is within striking distance of a return to the top 100.
She remains alive in the doubles event, partnering Slovene Andreja Klepac.
Matosevic, the world No.64, had no answers against Andujar, who was victorious 6-4 6-3 in one hour and 23 minutes.
The Spaniard converted 100 per cent of the break point chances he had, as well as saving both of the break points he faced.
Despite Matosevic banging down five aces, Andujar was more effective with his own delivery, landing more first serves and winning 81 per cent of his first serve points.
The Spaniard next faces No.7 seed Janko Tipsarevic.