KAANAPALI, Hawaii — After a World War II-era stanza of the German national anthem was sung during the opening ceremonies, the United States took a 1-0 lead and was ahead in the other opening match in its best-of-five Fed Cup quarterfinal Saturday.

Alison Riske beat Andrea Petkovic 7-6 (10), 6-2, and CoCo Vandeweghe led Julia Goerges 6-3, 3-1 when rain halted play.

The stanza brought a stern response from Petkovic, and an official statement of apology from the United States Tennis Association.

Petkovic, who was born in Bosnia, said in the German-speaking portion of her press conference that she considered walking off the court as the anthem went on.

“I thought it was the epitome of ignorance, and I’ve never felt more disrespected in my whole life, let alone in Fed Cup, and I’ve played Fed Cup for 13 years now and it is the worst thing that has ever happened to me,” Petkovic said after her loss.

— From wire reports