Down a set and a break, Larsson rallied to win 5-7, 6-4, 6-2 in the second round Wednesday. The 26-year-old Swede had lost her opening match in four appearances at Flushing Meadows before this year.
Once a sure bet to stick around for a while at Grand Slam tournaments, Stephens suddenly can't win there. The 21st-seeded American had reached the fourth round at six straight major events through this year's French Open, the longest active streak at the time. Then she dropped her opener at Wimbledon.
This was the second big women's upset of the day. Peng Shuai beat fourth-seeded Agnieszka Radwanska, the first top-10 player knocked out of the tournament.