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• Austrian hammers former world No1 Djokovic 7-6, 6-3, 6-0 in quarter-final • Rafael Nadal coasts through on injury retirement and is next up for Thiem

It is inconceivable to believe and ludicrous to suggest that Novak Djokovic will not rediscover the spiritual drive and technical facility that lifted him to the summit of his sport here only 12 months ago. But there were extended moments towards the end of the defending champion’s shocking three-set defeat against Dominic Thiem on the 11th day of the French Open when that prognosis seemed wholly valid.

Losing in the quarter-finals of a slam is hardly a disgrace. But when the third set screamed by in only 20 minutes there was a disturbing sense of surrender in the Serb’s demeanour. Later, his press conference felt like a wake that turned into a reading of the will, as Djokovic pondered his immediate plans, while giving his conqueror due respect.

While the 30-year-old expects to meet up again with Andre Agassi before Wimbledon, there was an air of uncertainty about their new partnership – which lasted precisely three matches here before the American returned home after fulfilling an engagement to promote a brand of coffee.

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Djokovic insists he knows what is wrong with his game but appears unsure how to fix it. When he won the title last year, Boris Becker and the Serb’s long-time friend and coach, Marian Vajda, headed one of the biggest support teams in tennis. Both are gone. So is Agassi. Djokovic looks alone, lost and vulnerable.

He admitted he felt “lost” when losing to Stan Wawrinka in the final of the US Open last year. But before that the world No41 Sam Querrey beat him at Wimbledon, and after New York, Denis Istomin (117) put him out of the Australian Open. At least he lost here to the No6 seed.

His dilemma can be distilled into the unfolding of that third set. Djokovic won eight points. He won six of 20 points on his own serve, two of 14 on his opponent’s. His sole, meagre success was to prevail in the one rally that went longer than nine shots. He hit 12 unforced errors, a third of his total for the entire match. The score tells the story of his weakening resistance: 7-6 (7-5), 6-3, 6-0 in only two and a quarter hours – the same time it took Hsieh Su-wei to beat Johanna Konta in the first round of the women’s draw.

Thiem played very well but, as Mats Wilander, who won this tournament three times in the 80s, observed, Djokovic played as poorly as he can have done “in the past seven or eight years”. He will drop to at least No3 in the rankings on Monday, possibly No4. He has not been outside the top two since he launched his magnificent assault on his opponents in 2011. It seems so long ago.

Thiem’s challenge, meanwhile, is to keep his composure for the semi-final on Friday against a rampant Rafael Nadal, who earlier had the benefit of a retirement result against his Spanish compatriot Pablo Carreño Busta when leading 6-2, 2-0.

As Thiem said courtside: “It’s amazing how difficult it is to go deep in a grand slam. You have to play the best guys round after round. It’s not getting easier on Friday.” It could not have been much easier on Wednesday.

There are moments when champions have to draw on the powers that make them special. Djokovic has recovered from unpromising positions so many times that even when he looked down and out, there was hope. Yet the passages of disappointment began to mount with such alarming regularity that, after a couple of hours, it seemed pointless to hold on to any notion of redemption.

Using the kick serve into the advantage corner, Thiem had drained Djokovic’s normally rock-solid backhand return. He invested a lot of his bread-and-butter strokes with a slice that confounded his opponent and he kept his own mistakes to a minimum, moving like a panther to hunt down the many short balls served up to him. But there was more going on than mere tennis shots.

The first set was close, although Thiem suspected this might not be the Djokovic who hit him off the court in the semi-finals in Rome recently. The Austrian had witnessed his opponent’s occasional struggles in the first week. This was his time. He stuck to his uncomplicated, robust shot-making and, gradually, forced Djokovic to drop deeper, then drilled home the angled winners.

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He might have been waiting for the backlash but it did not materialise. At 0-30 and two sets down, Djokovic played a blinding point to get back into the rally. The patrons applauded and the Serb, who lives for love, smiled and raised a defiant fist. But it did not have the fire of old. It was just that: a gesture. Thiem broke his serve, and maybe his heart.

If Djokovic had realistic ambitions beforehand of reaching the semi-finals, his primary objective now was to avoid embarrassment. His ground strokes disintegrated. The net grew larger and the court shrank. Thiem was not looking across at a legend who had won 12 slam titles and probably would collect a few more yet; he saw a wounded bull.

As the confident 23-year-old rested before the final act, leading 5-0, he looked as calm as Djokovic often has done in similar situations. There was no room for pity. He wanted a bloodless conclusion.

Thiem coasted to 40-0. Court Suzanne Lenglen, the tournament’s second arena, went silent. Would he not only bagel Djokovic but not allow him even one more point? Thiem netted a backhand, the smallest of mercies.

He missed a serve – and then he lashed an exquisite backhand down the line. The deed was done.

There were press-box mutterings: did we just see Djokovic give up? Surely not. He had, though, been beaten out of sight by a young man who one day might be as great a champion himself.