Spain's Olympic champion Carolina Marin and South Korea's Sung Ji Hyun suffered first round defeats at the Badminton World Federation (BWF) Australia Open at the Sydney Olympic Park Sports Centre.
Fourth seed Sung has been in impressive form throughout the season, but faced a tricky test against former world number one Saina Nehwal in the first round of the women’s event.
Nehwal, who is the defending champion in Australia, battled to a straight games 21-10, 21-16 victory in the contest.
“My ranking has dropped; I have to face top players in the first round," said the Indian.
"I have the game, I just need to get these matches.
"My condition is not at its best.
"In the second game my stamina was coming down, but I still managed to pull it out.
"I didn’t expect to cross the first round, now I'm looking forward to the next one."
Nehwal will face Malaysia’s Soniia Cheah in the second round, after she saw off the challenge of Hong Kong’s Cheung Ngan Yi by a 21-14, 21-15 scoreline.
Second seed Marin suffered defeat in the first round, losing 21-12, 21-19 to Japan’s Nozomi Okuhara.
Okuhara will face fellow Japanese player Minatsu Mitani in the second round, after her 21-13, 21-17 success against Chinese Taipei’s Hsu Ya Ching.
Top seed Tai Tzu Ying had no issues in reaching the second round.
The Chinese Taipei star earned a 21-18, 21-11 win over Scotland’s Kirsty Gilmour to set up a meeting with Ratchanok Intanon of Thailand in the second round.
South Korea’s Son Wan Ho, the men’s top seed, was forced to dig deep to secure his spot in the second round.
He eventually overcame qualifier Kashyap Parupalli 21-18, 14-21, 21-15 to seal a second round meeting with another Indian opponent in Srikanth Kidambi.
Denmark’s Jan O Jorgensen would exit the tournament, as the fifth seed retired when trailing 23-25, 21-12, 14-9 to Indonesia’s Anthony Sinisuka Ginting.
The Australian Open is a BWF World Superseries event.