Hyeon Chung is the first Korean to reach a grand slam semi-final after continuing his spectacular Australian Open run at Melbourne Park.
The 21-year-old world No.58 outclassed unseeded American Tennys Sandgren 6-4 7-6 (7-5) 6-3 on Wednesday to also become the lowest-ranked man to make the last four of the Open since Marat Safin in 2004.
Chung will play second-seeded titleholder and five-time champion Roger Federer or Czech Tomas Berdych on Friday night for a spot in the final.
