World No. 1 Iga Swiatek comes from behind to defeat Jule Niemeier, advancing to US Open quarterfinals

(CNN) Two-time grand slam champion Iga Swiatek has reached her first US Open quarterfinal in New York after escaping an upset by unseeded Jule Niemeier.

Niemeier took the opening set from reigning French Open champion Swiatek and threatened to stage the upset of the tournament after scoring the first break of the second set with a crosscourt forehand.

Monday marked the first time Swiatek, the player to beat in women's tennis this year, had dropped a set this tournament.

But the world No. 1 came back from a shaky start to beat Niemeier 2-6 6-4 6-1.

By the fifth game of the second set, Swiatek took four straight points, finishing with an ace, a forehand winner and another ace, before breaking the German in the next game.

Swiatek escaped an upset by Neimeier in the Big Apple.