"This mistake will not occur again," the United States Tennis Association tweeted on Saturday night local time in Hawaii after the organizers of the tennis tournament accidentally played the first stanza of the German national anthem, which has been banned in Germany since the end of World War II.

The error occurred during the opening ceremonies of the Fed Cup before quarterfinal play began between Alison Riske of the United States and Andrea Petkovic of Germany. Riske went on to defeat Petkovic in two sets (7-6, 6-2).

Hitler used the first stanza as Nazi propaganda

'Worst thing that has ever happened to me'

Upon hearing the first words of the WWII-era stanza,"Deutschland, Deutschland, über alles" ("Germany, Germany, above all else"), from the court, Petkovic reacted with dismay and anger.

"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 once the match ended, adding that she considered walking off of the court.

"It's 2017 - something like this simply should not happen in the United States," she added.

The German team and around 20 fans attempted to sing the correct words, "Einigkeit und Recht und Freiheit" ("Unity and justice and freedom"), over the amplified taboo verse.

German team coach Barbara Ritter added her condemnation of the incident to Petkovic's strong words.

"This is an absolute scandal, a disrespectful incident and inexcusable," Ritter said. "I could have sobbed. Hearing the national anthem at the Fed cup is a holy moment."

Multiple apologies from the USTA

In addition to an apology chain on Twitter, the USTA issued an official statement profusely apologizing for the gaffe.

"The USTA extends its sincerest apologies to the German Fed Cup team and all of its fans for the performance of an outdated national anthem prior to today's Fed Cup competition," it said. "In no way did we mean any disrespect. This mistake will not occur again, and the correct anthem will be performed for the remainder of this first-round tie."

cmb/tj (AFP, AP)