The United States Tennis Association apologized on Saturday for introducing a Fed Cup match with a portion of Germany’s national anthem that was once used as Nazi propaganda.

Fans and players appeared visibly upset as an opera singer belted out the controversial, outdated first verse in German: “Germany, Germany, above all, above all in the world.” People attending the event in Hawaii were seen attempting to sing over the performer.

The “Deutschlandlied” lyrics were written in 1841, nearly 100 years before Adolf Hitler’s Nazi Party took control of Germany. But the Nazis later made that first verse their own, weaving it into their party’s song.

YouTube Members of Germany's tennis team, as well as fans, appeared to try to sing over the outdated verse with their country's modern anthem.

”Deutschlandlied” was briefly banned after World War II. Now, only its third verse is included in the country’s national anthem.

German player Andrea Petkovic later expressed outrage over the performance and said she considered walking off the court, according to the Associated Press.

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

USA Today Sports / Reuters German tennis player Andrea Petkovic, seen during Saturday's match, later said that she considered walking off the court during the singer's performance.

The USTA later issued a statement to apologize for what happened.

“We extend our sincerest apologies to the German Fed Cup team and all of its fans for the performance of an outdated National Anthem prior to today’s Fed Cup competition,” it read. “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.”

The USTA extends a sincere apology to the German Fed Cup team & fans 4 the outdated National Anthem. This mistake will not occur again. pic.twitter.com/4LyG3ACe5u — USTA (@usta) February 11, 2017