Edmund had fought back from a set down to the world No 4 to forced a decider and Dimitrov was serving at 4-4 when disaster appeared to strike.
The British No 2 was initially by a Dimitrov forehand and as he tried to change direction, jarred his ankle and screamed in pain.
His Bulgarian opponent quickly ran to help him up and to his chair, where the physio began to assess the injury.
Worryingly for Edmund fans, the 22-year-old told his medical professional he had “heard a crack” when it happened, sparking fears he might have damaged a ligament or even broken a bone.
However, after being given a medical timeout and a strapping around the stricken joint, Edmund jogged back to the baseline to resume the match, which was delicately poised.
He appeared not to have suffered a serious injury, playing on with a near-full range of movement.
But Dimitrov was not to be denied and immediately broke serve to secure a 6-3, 6-7, 6-4 win over Edmund and book a semi-final against Nick Kyrgios.
Edmund will be hoping he has not sustained any serious damage to his right ankle with just 10 days to recover before the Australian Open.
By beating Colombia’s Santiago Giraldo in the first round, he secured his first ever main draw win at the tournament last year, a feat he repeated at Wimbledon after reaching the third round of the French Open.
That string of career-best performances saw him rise back into the top 50, a place he will hope to cement in the early part of 2018.
But first he will have to ensure he is fit, unlike British No 1 Andy Murray, who pulled out of the Australian Open earlier this week with an ongoing hip problem.