She added, “I have to be the greatest, whether it’s against the second seed, the No. 1 seed, or the No. 80th player in the world. I have to show up, or else I’m going to go home.”

Only No. 1 Naomi Osaka and No. 5 Elina Svitolina remain from the top five women’s seeds. Svitolina defeated No. 10 Madison Keys, 7-5, 6-4, on Sunday night.

On the men’s side, No. 3 Roger Federer avoided Barty’s fate and needed three fewer minutes to dismiss David Goffin in three sets, 6-2, 6-2, 6-0. It was Federer’s most dominant performance of the tournament so far and he is back in the quarterfinals after last year’s surprise fourth-round defeat to John Millman.

Federer’s next opponent is Grigor Dimitrov, who beat Alex de Minaur, 7-5, 6-3, 6-4, in their fourth-round match. Also, No. 5 Daniil Medvedev, the do-it-yourself villain of the tournament, beat Dominik Köpfer, 3-6, 6-3, 6-2, 7-6 (2), in Louis Armstrong Stadium, and then taunted the crowd for booing him, as he did in his previous match.

Medvedev is embracing his new role as bad guy. He told the audience in an on-court interview that he was suffering from a shoulder injury and that the fans’ negative energy motivated him to play through it and win. He also requested they continue to boo him in his next match, against No. 23 Stan Wawrinka. The fans responded to Medvedev by booing more, but most of the fans were smiling and playing along.