American star Jessica Pegula shocked world No.1 Iga Świątek 6-2 6-7(4) 6-4 in the semifinals of the Canadian Open in Montreal on Saturday, but perhaps the biggest shock of the day came when a classic song began blaring through the on-court speakers midway through a point.

With Pegula 4-3 up in the second set tiebreak and having just wrongfooted Świątek with a lob, “Cotton Eye Joe” began playing on court, forcing the umpire to call a let while the song continued, and the crowd murmured in disbelief.

“I just thought it was funny,” Pegula said afterwards, according to Reuters.

“I’ve never had that happen, let alone with ‘Cotton-Eye Joe.’ I was like: ‘Is this really happening right now?’ Of all the songs. It was just like: ‘What is going on?’

“Yeah, it was a bummer because I hit a really good lob and she barely got it, and I had a really good play on the ball, and she was kind of out of position from the lob that I hit.”

The point was replayed and that seemed to derail Pegula’s second set tiebreak, as Świątek won the next 12 points in a row, a run that included leveling the match at a set apiece.

Świątek continued to ride this momentum, taking a 4-2 lead in the deciding third set but Pegula won the last four games, and 16 of the last 19 points of the match, to seal victory.

“She really pushed me, so I needed to change something up,” Świątek said afterwards, according to the WTA’s website.

“It was working, but in the third, I don’t really know what happened when I was leading. I’ve got to watch the match and analyze it, because for sure she was fighting for every point and I did as well. It was a tricky match.”

It was Pegula’s second victory over Świątek this year, and she will now advance to her third WTA 1000 final where she will face either Elena Rybakina or Liudmila Samsonova, as she seeks to become the first American to win this tournament since Serena Williams in 2013.