US Open champion Emma Raducanu was sensationally beaten in her first match following her Flushing Meadows triumph, going down in straight sets to Aliaksandra Sasnovich at the Indian Wells Open on Friday.

The Belarussian, who is currently ranked 100th, stunned the 19-year-old Briton 6-2 6-4 in one hour and 25 minutes.

Raducanu had been on a 10-match winning streak coming into her maiden Indian Wells campaign.

"I'm still so new to everything. The experiences that I'm going through right now, even though I might not feel 100 per cent amazing right now, I know they're for the greater good," Raducanu said after the defeat.

"I mean, I'm 18 years old. I need to cut myself some slack."

Raducanu, who did not drop a set during her US Open run, appeared in control early after winning the opening six points, but Sasnovich claimed the first break in the third game.

Unforced errors proved costly for Raducanu as the clean-striking Sasnovich capitalized to win the first set, before opening the second set with another break.

Raducanu responded with an immediate break back and led 4-2 in the second set, before the Belarussian hit back by winning the next four games to topple the British teenager.

"It was a really good match for me. I play really well," Sasnovich said. "I know she just won US Open. I lost there in the first round. But I tried to go on court, I tried to enjoy. I did everything right."

FORMER WINNER HALEP PROGRESSES

Sasnovich will face two-time Grand Slam winner Simona Halep in the third round after the Romanian defeated Marta Kostyuk 7-6 (7-2) 6-1 in one hour and 33 minutes.

The 11th seed, who split with long-time coach Darren Cahill last month amid an injury-disrupted year, was down a break early before working her way back and dominating the tiebreak.

Halep broke twice in a more controlled second set to claim victory in her 10th appearance at Indian Wells.

"I missed a lot playing tennis at this level this year because I've been injured and many months, I couldn't play matches," said Halep, who won at Indian Wells in 2015. "I came here a little more aggressive than normal and I'm trying to improve my game and myself."

KVITOVA CRUISES AS TOP SEEDS WIN

Two-time major winner Petra Kvitova eased into the last 32 with a 6-2 6-2 triumph over Arantxa Rus from the Netherlands.

Seventh seed Kvitova set up a showdown with two-time Australian Open champion Victoria Azarenka after she beat Magda Linette 7-5 3-0 in a walkover. Kvitova leads Azarenka 5-3 in head-to-head battles.

Second seed Iga Swiatek dominated Croatian Petra Martic 6-1 6-3 to seal her passage into the third round, while fourth seed Elina Svitolina got past Teresa Martincova 6-2 7-5.

Beaten 2021 US Open finalist Leylah Fernandez triumphed over experienced Frenchwoman Alize Cornet 6-2 6-3 and will play ninth seed Anastasia Pavlyuchenkova in the third round after she easily accounted for Madison Keys 6-3 6-1.