The 17-year-old Andreeva underlined her rich potential by defeating former world number two Ons Jabeur of Tunisia 6-4, 7-6 (7/2) in a high-quality encounter.

Andreeva will now play either world number one Aryna Sabalenka or Czech Marie Bouzkova.

With the Australian Open just over a week away, Dimitrov moved through when home hope Jordan Thompson retired injured in their quarter-final.

Jabeur was runner-up at Wimbledon in 2022 and 2023 but has been out of action since August with a shoulder injury.

Andreeva was able to deal with the tricky shotmaking of Jabeur, breaking her once in the first set and then recovering from two breaks of her own serve in the second set to force a tiebreak.

She raced through the tiebreak to wrap up the match in 90 minutes.

“It was a really tough match, especially mentally, because it’s always hard to play against a person that you like,” Andreeva said.

“It was mentally hard to keep pushing and playing aggressively because we all know that she’s very good at playing games — drop shots, slices.

“I just wanted to play solid. I’m not sure if that was consistent today, but I kept trying.”

The second women’s semi-final will be between Russian qualifier Polina Kudermetova and Ukraine’s Anhelina Kalinina.

In the men’s draw, Dimitrov had a far easier passage when Thompson was forced to retire with the Bulgarian ahead 6-1, 2-1.

Dimitrov, who has won the Brisbane title twice before, will play Czech Jiri Lehecka in the semi-finals.

The Australian Open starts on January 12.