The third seed had hardly put a foot wrong in his first four matches but he made a bad start and never found anything like his best form.
Dimitrov took full advantage, his game as good as Murray’s was poor, and the Bulgarian showed his growing maturity to take control in the decisive moments at the end of the second set and win 6-1 7-6 (7/4) 6-2.
While Dimitrov moves through to his first grand slam semi-final against Novak Djokovic tomorrow, Murray must begin the inquest into what went wrong.
The worrying thing for the Scot is it is becoming a trend.
His break from the game to undergo back surgery is undoubtedly a factor but, since the ultimate high of beating Novak Djokovic to win Wimbledon 12 months ago, Murray has not beaten a top-10 player or reached a final.
In the last four grand slams, he has lost three times in the quarter-finals and once in the semi-finals and has managed to take just one set in all those matches.
The 27-year-old said: “I need to go away and make a lot of improvements in my game. I’ve lost a couple of matches in the last few slams where I’ve lost in straight sets and played poorly.
“So I need to have a think about things, what are the things I need to improve, and get myself in better shape and work even harder. Because everyone’s starting to get better. The younger guys are now obviously becoming more mature and improving all the time.
“I don’t feel like I have improved so much since Wimbledon last year, I think I’ve played some very good tennis but also some ordinary stuff.
“But if I’m going to play better tennis than I am just now, the only way to do that is by working even harder than I have before. Getting in the gym, getting stronger, becoming physically better.”
There were no such problems for Roger Federer who reached a ninth semi-final after beating his great friend Stan Wawrinka in an all-Swiss battle on Centre Court.
The seven-time champion has never lost at the last-four stage at the All England Club and gave himself the chance to reach another final after taking national bragging rights with a 3-6 7-6 (7/5) 6-4 6-4 victory.
“Stan played great, especially for the first two sets,” said Federer. “After that he started to struggle maybe a little bit with his fitness.”
With Rafael Nadal and Andy Murray already out, there was a point yesterday when both Federer and Novak Djokovic – the other members of the ‘big four’ – were in danger of tumbling out too.
Djokovic dug himself out of a deep hole though (winning 6-1 3-6 6-7 (4/7) 6-2 6-2), and Federer seized charge against Wawrinka once he levelled the contest in their second-set tie-break.
Wawrinka, who had been struggling physically, dug deep at the end to save four match points.
But on the fifth Federer followed up a scorching serve, that Wawrinka did well to float back, with a lethal smash from mid-court.
Meanwhile, in the women’s singles, Eugenie Bouchard and Simona Halep will go head to head today for the prize of a place in the final.
Both were impressive winners of their quarter-finals yesterday, as Bouchard brushed past Angelique Kerber 6-3 6-4 and Halep reeled off the final 11 games in a resounding 6-4 6-0 victory over last year’s runner-up Sabine Lisicki.
Bouchard overwhelmed Kerber, conqueror of Maria Sharapova in the fourth round, with a performance that showed why she looks destined to win grand slams sooner rather than later.
After last-four showings at the Australian and French Opens already this year, Bouchard has made it a hat-trick and Roland Garros runner-up Halep may have her hands full in preventing the 20-year-old Canadian reaching a maiden final.
It took Bouchard an hour and 12 minutes on Court One to come through and set up what she agreed was an attractive last-four showdown.
“I’m excited, she’s a very good player, three in the world,” Bouchard said. “I’m excited to be in the semis (of a grand slam) again and I want to go one step further, that’s for sure.”