Sinner started the match as the heavy favourite after a week of serene progress.
The 23-year-old had dropped just 17 games and spent only five hours and 23 minutes on court – less time than the entirety of his epic French Open final against Carlos Alcaraz – on his way to reaching the fourth round.
But it was a different story against the experienced Dimitrov – the first seeded player Sinner has come up against so far.
Dimitrov was alert, adaptable and quick, returning everything Sinner threw at him in a dominant display, and a break of serve at the first opportunity stunned a crowd expecting to watch another demolition job.
It proved to be decisive as Dimitrov produced a magnificent serving display, saving the sole break point he faced before closing out the first set.
Sinner looked nervy and, with Dimitrov refusing to let his level dip as he went an immediate break up, he struggled to find any momentum to get back into the contest.
Sinner called for a medical timeout midway through the second set and was in visible discomfort with his elbow. However, he recovered well enough to break back as Dimitrov served for the set at 5-4 up.
That was quickly forgotten when Dimitrov broke again, then hung in a tough service game to hand Sinner the exhausting task of overturning a two-set deficit – something he does not have a strong track record in.
A 10-minute break to close the Centre Court roof then followed as the light faded with Dimitrov in the driving seat and playing some of his best tennis in years.
He served an impressive 14 aces in the match and it was that which perhaps proved to be his downfall as he sat down clutching his pectoral muscle having sent one down to hold at 2-2 in set three.