Zarina Diyas and Heather Watson were the seeded casualties on the first day of main-draw action at the Family Circle Cup in Charleston. Diyas, the 11th seed from Kazakhstan, won the first set against Czech qualifier Lucie Hradecka but was beaten 4-6 6-1 6-3. British number one Watson, seeded 16th, gave up 14 break points and lost her serve seven times en route to a 6-3 4-6 7-5 defeat to Croatian teen Donna Vekic in a hard-fought match lasting more than two and a half hours. Heather Watson crashed out in Charleston after a narrow victory to Donna Vekic . The other seeds in action, Irina-Camelia Begu and Mona Barthel, progressed in straight sets. Begu, seeded 13th, required two hours and a second-set tie-break to win 6-2 7-6 (7/5) against German qualifier Laura Siegemund, who had hammered Japanese veteran Kimiko Date-Krumm 6-0 6-1 to reach the tournament proper. Barthel, two places lower than Begu in the seedings, broke serve four times in a 6-3 6-3 win over Hungary's Timea Babos. Chanelle Scheepers of South Africa won 6-2 2-6 6-4 against New Zealand's Marina Erakovic while Croatian Ajla Tomljanovic beat Romania's Alexandra Dulgheru 7-6 (7/5) 4-6 6-4. There was an easier time for Diyas' Kazakh compatriot Yaroslava Shvedova, who beat Switzerland's Stefanie Voegele 7-5 6-2. The two all-American ties ended with Lauren Davis beating Grace Min and wild-card Sachia Vickery victorious against qualifier Jessica Pegula, both in three sets. Shelby Rogers brushed aside Spain's Silvia Soler-Espinosa 6-3 6-1 but Irina Falconi was dismissed just as comfortably by Tatjana Maria of Germany and Nicole Gibbs and Christina McHale lost in straight sets to Shuai Zhang and Danka Kovinic respectively. Kristina Kucova beat Mirjana Lucic-Baroni while Evgeniya Rodina saw off Yulia Putintseva. The last match of the evening went the distance with Ukrainian qualifier Kateryna Bondarenko eventually beating Alison Riske of America 6-4 4-6 6-1 after two hours on court.
The British No 1 was edged out in a keenly fought contest  which lasted two-and-a-half hours .
Vekic won 6-3, 4-6, 7-5 to eliminate the 16th seed .
She will play either Madison Brengle or Edina Gallovits-Hall .