NEW YORK, Aug. 30 (Xinhua) -- Wimbledon champion and world number four Angelique Kerber from Germany held off an incredible challenge by Sweden's Johanna Larsson to advance into the third round of the U.S. Open women's singles here on Thursday afternoon.

Kerber, the 2016 U.S. Open champion, survived a determined effort from 83rd-ranked Larsson, 6-2, 5-7, 6-4 in Arthur Ashe Stadium.

Kerber led Larsson 6-2, 5-2, and had a pair of match points in the second set before being extended deep into a decider. The German incredibly lost her last four service games of the second set.

Buoyed by a pair of dramatic saves to keep her alive, Larsson continued her momentum into the final set. She held serve from 0-40 down to begin the final set. But Kerber stepped to the line to serve out the match proved to be the charm, as she rallied from 0-30 down in the set's final game to seal victory.

Kerber needed two hours and 23 minutes to book her spot in the third round opposite No. 29 seed Dominika Cibulkova, who won a similar marathon in the heat to beat Hsieh Su-Wei from Chinese Taipei, 7-6, 4-6, 6-4.

"I think we both really played on a really high level from the first point," Kerber said. "In the end it was one or two points to decide the match."

With temperatures flirting with 37 degrees Celsius on Thursday, U.S. Open organizers again implemented an extreme heat policy, which both players took advantage of after the second set.

The policy allows players to take a 10-minute heat break - the women between the second and third sets and the men between the third and fourth sets.