Improbable victory by 97th seed at Australian Open

A 21-year-old South Korean has beaten Novak Djokovic at the Australian Open in one of the biggest shocks of the tournament so far. Hyeon Chung became the first South Korean to ever reach the quarter-finals of a grand slam when he beat Djokovic in three straight sets. In another upset, the 97th ranked Tennys Sandgren - that really is his name - has knocked out the fifth-seed to become the second debutant to reach the quarter-finals at the Australian Open in 20 years. For more on the day's action we're joined from Melbourne by correspondent Dave Luddy.