Top seed Simona Halep won through to the second round of the Citi Open before rain ended play prematurely in Washington.
World number two Halep opened her campaign with a 7-6 (7-3) 6-0 win over 2015 champion Sloane Stephens on Tuesday.
Stephens battled bravely in her first hardcourt tournament since the Olympic Games in Rio due to a foot injury but 48 unforced errors cost the American dearly.
Next up for Halep is Mariana Duque-Marino for a spot in the quarter-finals.
Only three other matches were completed before rain wreaked havoc in the American capital.
Ekaterina Makarova prevailed 7-6 (7-4) 6-3 against Jamie Loeb, Monica Puig accounted for Louisa Chirico 6-4 6-4 and Heather Watson lost 7-6 (7-4) 7-6 (7-3) to Patricia Maria Tig.
Among the players unable to take to the court were Eugenie Bouchard (against Christina McHale), Sabine Lisicki (versus Valentini Grammatikopoulou) and Kristina Mladenovic (against Tatjana Maria).