By the day, almost by the hour, the cracks in the edifice of modern tennis are widening. Andy Murray, playing his worst match at Wimbledon in several years, followed the world No 1 Rafael Nadal out of Wimbledon on Wednesday in three sets that detained young Grigor Dimitrov barely two hours on Centre Court while on an adjacent battlefield the favourite Novak Djokovic needed all five sets to get rid of the No 26 seed Marin Cilic.

This is getting serious – but Murray might have most to worry about. Against a rising star who played with the same lack of fear the Australian teenager Nick Kyrgios showed in dispatching Nadal on Tuesday, Murray had no answers, and the Bulgarian won with alarming ease: 6-1, 7-6, 6-2.

Dimitrov will now leapfrog Murray into the top 10, with the Scot slipping to 10th for the first time in six years. It is not a full-scale crisis but there must be concern in his camp, given he has not won a tournament since he beat Djokovic in the final here a year ago.

He has recovered fully from back surgery last September and his coach, Amélie Mauresmo, seems to have settled in well in the few weeks they have worked together. They will decide over the next few days whether or not to make their short-term arrangement more permanent, and Murray sounded later as if he would like it to continue. It would be a blow if Mauresmo did not think so too, given the crushing effect on the player of Ivan Lendl’s sudden departure in March. Still, by Murray’s own blunt admission after the quarter-final, Dimitrov, was “the better player from start to finish”.

Murray won only three out of every 10 second serves, three of his five double faults came in the weary conclusion and robbed of consistent potency with ball in hand, he had to scrap for every point. He blinked in the face of heavy, quality fire, although he took his licks pretty well.

Playing as if invaded by some foreign virus that had drained his tennis brain and paralysed his normally smooth movement over the grass of his favourite tournament, he could not resist Dimitrov’s educated power and sharp, well-hidden switches of direction that kept him guessing in every exchange.

At times, Dimitrov really did look like Roger Federer, to whom he has been compared for so long. “Andy is a friend,” Dimitrov said. “It’s a tough feeling when you know the person outside of the court. But I have more matches to play and I’m going to just prepare for the next one.”

At Dimitrov’s age, 23, Murray had made a significant move, ranked No 4 at the height of the Federer-Nadal hegemony, and he had already played in a slam final, losing to Federer in New York. But Dimitrov has been a classic late developer, the owner of only four titles. He has never been in a hurry, either in the shot or advancing on the game’s elite.

The question mark was: could he handle the pressure of his second slam quarter-final against a member of the Big Four? He had almost beaten Nadal at this stage in Melbourne but when he took 10 serves to get on the board at the start, and was forced to save a break point, we wondered. And when Murray held to love it was tempting to imagine this might set the tone of the match. It did not quite go that way.

What Dimitrov has in abundance is self-belief just short of arrogance and it was adventure that got him the break in the fourth game. He was hitting his shots crisply and forcing Murray to shift uneasily side to side.

When Dimitrov held to love for 4-1 his confidence soared and he had Murray suffering in the next game, the Scot pushing two slack forehands into the net from deep for the second break. Dimitrov, buzzing now, sealed the set with a smash at the net. Murray was in deep trouble.

He kept eight out of 10 service returns in court during that blitz but too often fell back on his old default mindset of grind rather than risk – and Dimitrov punished him for his negativity. The challenge for the champion was to get a grip on this runaway thoroughbred; the Bulgarian’s task was to keep Murray guessing about the speed, depth and angle of his ground strokes.

It took Murray five games into the second set to find his feet properly, moving with more assuredness behind a serve that briefly clicked, despite a couple of double faults. They swapped breaks but Murray needed more than parity.

He had to rattle Dimitrov, somehow make him feel uncomfortable on the big stage. But his tormentor was playing exuberant, irresistible tennis. All the anxiety was with Murray – and it mounted when, forced deep again, he netted a backhand. He somehow scrambled to deuce and delighted in forcing Dimitrov to chase in vain from one side of the court to the other to go 6-5 up. For the first time in the match Dimitrov, behind in the serving cycle, was under points pressure. He held to force the tie-break.

In a tense duel, the world No 13 produced a glorious passing shot then a sublime drop volley to grab a two-set lead. Murray has come back to win from two sets down on seven occasions. Not this time.

When he went 4-2 behind in the third, the will seemed to leave him. Even with Dimitrov slipping on the dusty turf behind the baseline, Murray found himself unable to put the ball away in one rally in the seventh game – and needed a double fault by the Bulgarian to retain a sliver of hope. But he continued to slice long and bash wide, squandering one opportunity after another and with the clock ticking towards the second hour, he had to hold to stay in the tournament.

The crowd desperately wanted him to survive, but he was doing little to encourage their slim hopes. Mauresmo must have been as bemused as everyone in the house when he hit his fifth double fault to hand Dimitrov two match points. He saved the first with a forehand that dipped inside the deuce corner – and then lashed a final, limp effort into the middle of the net. It was a tame surrender – such a contrast to his efforts here a year ago – but a memorable day for Dimitrov and all those who believe he might have the stuff of greatness about him.

Big-serving Milos Raonic powered past Nick Kyrgios 6-7 6-2 6-4 7-6 to end the Australian teenager’s Wimbledon adventure and book his first Grand Slam semi-final.

The Canadian eighth seed called upon his huge serve to thump down 39 aces, conceding only one break against the 19-year-old upstart who had rocked the All England Club with the previous day’s triumph over Nadal.

Both Kyrgios and Raonic, 23, were playing the day after their fourth-round matches, but the Australian’s exertions to claim his momentous win appeared to have taken a physical and emotional toll on the youngest player in the men’s draw.

Raonic, who reached the last eight at the French Open last month, is the first Canadian to reach the men’s semi-finals of a Grand Slam in the professional era and now faces seven-times champion Federer on Friday for a place in the final.

Federer finally blotted his copybook on Wednesday, dropping a set for the first time at this year’s championship before reaching the semi-finals with a 3-6 7-6(5) 6-4 6-4 win over fellow Swiss Stanislas Wawrinka.

It is the ninth Wimbledon semi-final for the 32-year-old seven-times champion, who has been in imperious form on the grass this year, winning at Halle before steaming through five rounds at the All England Club.

(Guardian Service)