Defending champion Yun Mi-jin equalled her own Olympic record in the individual archery on Tuesday, scoring 173 out of 180 points.
The South Korean achieved maximum 10-point scores with 12 of her 18 arrows in defeating Japan's Sayami Matsushita in the second-round shoot-out.
Meanwhile, Britain's Laurence Godfrey is through to the last 16 of the men's individual competition.
He shot a nine with his last arrow to edge Sweden's Magnus Petersson.
Yun, 21, is aiming to become the second woman archer to win four Olympic golds in the modern era.
Since first competing at the Games in 1984, South Korea's women have won all nine individual and team gold medals - a feat unmatched in any other sport.
Compatriots Park Sung-Hyun and Lee Sung-Jin also eased through, beating Russia's Natalia Bolotova (165-148) and Elpida Romanitzi of Greece (166-146) respectively.
However, there was disappointment for Bhutan whose only two competitors at the Games crashed out - Tshering Chooden in the women's event and then Tashi Peljor in the men's.
Chooden went down in a tie-break to India's Reena Kumari losing 7-4 after both archers had been locked at 134-134.
In the men's competition, while Godfrey advanced, world champion Michele Frangilli bowed out.
Former world champion Park Kyung-mo survived a tiebreak against unfancied Kazakh Stanislav Zabrodskiy, and top seed Im Dong-hyun also won.
There was further good news for Britain as Alison Williamson and Naomi Folkard progressed in the women's individual event.
Williamson, a primary school teacher from Church Stretton, Shropshire, gave Japan's Sayoko Kawauchi a lesson during their last-16 elimination round match.
The Briton, ranked 21, chalked up 154 points to 53rd-ranked Kawauchi's 150.
And Folkard, a music student from Leamington Spa who is ranked 17th, beat Finland's 49th-ranked Mari Piuva by 156 points to 151.