World number 1 and defending champion Novak Djokovic has moved into the semi-finals of the Australian Open with a victory over Tomas Berdych 6-1 4-6 6-1 6-4. Djokovic will now play fourth seed David Ferrer who came back from two sets down to beat fellow countryman Nicolas Almagro 4-6 4-6 7-5 7-6 6-2.