The 19-year-old Briton, whose US Open defence collapsed in the first round last month, won 6-2, 6-4 to make the last 16 in Seoul.

The sixth seed will face Yanina Wickmayer of Belgium.

Raducanu reached a career-high 10th in the world, but is now 77th, having failed to build on her shock success at Flushing Meadows last year.

After rattling through the first set, the teenager picked up the pace in the second to surge into a 5-0 lead in less than 20 minutes.

A Raducanu double-fault in the sixth game gave Uchijima a whiff of survival and the Japanese won four straight games, before Raducanu finally sealed the match with a 114-kmph ace.

The match lasted one hour and 18 minutes.

Raducanu burst onto the scene last year when she made history by emerging from qualifying to claim a maiden Grand Slam title.

It was the first time a qualifier had won a major.