Dimitriov, 34, was on course to cause a major upset at the tournament as he was leading with two sets in his match with the first seed, 23, though the tearful player was forced to pull out of the game after suffering an injury - allowing Sinner to move on to the quarter-finals.
However, Sinner has now admitted he doesn’t feel like he can celebrate his progress, and has dubbed Dimitrov’s injury as “very unfortunate”.
Reflecting on the result after the match, Sinner said: “I don't take this as a win at all, this is just an unfortunate moment for all of us to witness.
“He has struggled in the last Grand Slams with injuries a lot, so seeing him again with this injury is very tough.
“We all saw by his reaction how much he cares about the sport. He is one of the hardest-working players on tour and it is very unfortunate.”
Sinner - who has become the ninth man in the Open era to reach seven consecutive Grand Slam quarter-finals - added: “This is not the end we wanted to see and it's very sad. We all wish him only the best.”
After two hours of play, Sinner was trailing behind the 19th seed 6-3 7-5 2-2, and it was looking increasingly likely Dimitrov would emerge victorious before he fell to the floor in pain.
After leaving for a medical timeout, Dimitrov - who retired from his fourth-round match against Daniil Medvedev at the All England Club due to a knee injury 12 months ago - reappeared in tears, knowing his chances at securing the Grand Slam were over.
Sinner - who will face the 10th seed Ben Shelton in the quarter-finals -said of Dimitrov: “I don't know what to say because he is an incredible player and we all saw this today. He has been so unlucky in the past couple of years. He is a good friend of mine and we understand each other very well off the court too.
“Seeing him in this position, if there was a chance for him to play in the next round he would deserve it. Mostly, I hope he has a speedy recovery.”