Okuhara, who won her maiden world title last month, is seeded eighth at Seoul's SK Handball Stadium and came through a tight clash with American Zhang Beiwen.

The 22-year-old eventually proved to be too strong, winning 21-19, 21-17.

All seven of the top seeds made it through although Spain's Olympic champion Carolina Marin, who was seeded fourth, withdrew before the Super Series tournament began.

Chinese Taipei's world number one Tai Tzu-ying knocked out another Japanese player as she sent Saena Kawakami packing.

The top seed won 21-19, 21-16.

Second seed and defending champion Akane Yamaguchi, also of Japan, won her clash against Russian Evgeniya Kosetskaya, 21-18, 21-15.

India's PV Sindhu, the Olympic silver medallist who also lost to Okuhara in the world final in Scottish city Glasgow, eased through as the fifth seed.

She beat Hong Kong's Cheung Ngan Yi 21-13, 21-18.

In the men's draw, South Korea's world number one Son Wan-ho began his quest for victory on home soil by knocking out China's former youth world mixed team gold medallist Huang Yuxiang.

Son, the top seed, had too much for the Chinese player, winning 21-18, 21-16.

With Malaysia's triple Olympic silver medallist Lee Chong Wei, the second seed, and Denmark's world champion Viktor Axelsen, the third seed, both withdrawing, the path looks open for Son.

He was boosted further when Chinese Taipei's fourth seed Chou Tien-chen was knocked out.

Chou lost to France's Brice Leverdez, who stunned Lee in the first round of the Glasgow World Championships, 23-21, 21-14.

Sixth seed Angus Ng of Hong Kong won a marathon encounter with Indian Prannoy Kumar before sealing his spot in round two.

Ng eventually triumphed 21-17, 21-23, 21-14.

Action in the South Korean capital continues tomorrow.