Unseeded Czech player Jiri Lehecka was leading 6-4, 4-4 when the Bulgarian left the court with the physiotherapist for a medical timeout.

Dimitrov, ranked No 10 in the world, returned but played one point before retiring.

Lehecka will play either American Reilly Opelka or Giovanni Mpetshi Perricard of France in the final, both very tall men with massive serves.

It will be the 23-year-old’s fourth final on the ATP Tour and he will be aiming to add the Brisbane title to his Adelaide win last January.

“I will need to be focused 100% all the time,” Lehecka said about facing Opelka or Mpetshi Perricard in the final.

“I will need to focus on every point, every chance, because the chance can be gone in a very small moment.

“I think for me the most important thing will be to focus on my own service games, then try to figure something out on return.”

Russian qualifier Polina Kudermetova continued her fairytale week when she beat Ukraine’s Anhelina Kalinina 6-4, 6-3 in the first women’s semifinal.

She has now won seven matches in a row at this week’s tournament but will have a big step up in class in the final against either world No 1 Aryna Sabalenka or Russian teenage sensation Mirra Andreeva.