Stuttgart – CoCo Vandeweghe put aside her career-long dislike of clay to crush US Open champion Sloane Stephens 6-1, 6-0 with a 56-minute rout in the first round of the Stuttgart Grand Prix on Wednesday.
There was a similar fate for last year's New York runner-up, with Russian Anastasia Pavlyuchenkova eliminating American Madison Keys 7-6 (9/7), 5-7, 6-4.
Vandeweghe and Stephens, who won the Miami title last month after a lacklustre six months following her Grand Slam triumph, had teamed up at the weekend to help the United States defeat France and reach the Fed Cup final.
"I really don't like clay, it's my least favourite surface," the Californian said after defeating the seventh seed.
"I'll never like it. This is my second time in Germany — I'm not here for the clay, it's more the shopping.
"I didn't come out here to play and lose."
Vandeweghe broke six times in her victory and next faces defending champion Laura Siegemund of Germany in the second round.
Vandeweghe increased her career record over Stephens to 4-1.
The unseeded Keys lasted for two and three-quarter hours before going down to Pavlyuchenkova in their second meeting.
In other first-round results, Russian qualifier Veronika Kudermetova surprised Spain's Carla Suarez Navarro 7-6 (7/5), 6-2 and Kazakhstan's Zarina Diyas downed Germany's Carina Witthoeft 6-3, 6-2.
Results from the WTA Stuttgart Grand Prix on Wednesday (x denotes seeding):
Coco Vandeweghe (USA) bt Sloane Stephens (USA x7) 6-1, 6-0
Veronika Kudermetova (RUS) bt Carla Surez (ESP) 7-6 (7/5), 6-2
Zarina Diyas (KAZ) bt Carina Witthoeft (GER) 6-3, 6-2
Anastasia Pavlyuchenkova (RUS) bt Madison Keys (USA) 7-6 (9/7), 5-7, 6-4