Qualifier Karatsev stuns Dimitrov to reach Melbourne semis

Aslan Karatsev continued his sensational run at the Australian Open when he stunned Grigor Dimitrov 2-6, 6-4, 6-1, 6-2 to become the fifth qualifier to reach the last four.

The world number 114 regrouped after an error-filled opening set to add the 18th seed to his list of upset victims at Melbourne Park and set up a clash with Novak Djokovic or Alexander Zverev for a place in the final.

Dimitrov looked shell-shocked as the Russian tightened up his game and pounded howitzer shots over the net -- faltering on serve and wandering around the Rod Laver Arena court listlessly in the 30 degree Celsius heat.

The 29-year-old Bulgarian took a medical timeout for treatment on his back after losing the third set but Karatsev would not be denied as he became the lowest-ranked player to reach a Grand Slam semi-final for two decades.