A year ago, Djokovic became the first man in nearly a half-century to claim a fourth consecutive major championship and completed a career grand slam at Roland Garros.
But his form has dipped considerably since then, and now he has gone four majors in a row without earning a trophy.
"It’s a fact that I’m not playing close to my best," Djokovic said. "This is a whole new situation that I’m feeling."
On Wednesday at a windy Court Suzanne Lenglen, Djokovic was out of sorts in so many ways, even before that 20-minute third set in which he won only eight of 34 points. That was only the second time that Djokovic lost a final set by the score of 6-0 in his 937 career tour-level matches.
"It was not there for me today," Djokovic said with a sigh.
He wasted two set points in the opener. By the end of the match, he wound up with nearly twice as many unforced errors, 35, as winners, 18. His backhand was particularly problematic.
Known for tremendous footwork and court coverage, the No 2-seeded Serb even stumbled and tumbled to the court, his racket flying out of his hands, early in the second set. Djokovic was left on his knees, and soon he would be out of the tournament entirely.
"All in all," Djokovic said, "it was decided, I think, in the first set."
How unlikely was this result?
Djokovic entered the day having won all five previous matches – and 11 of 12 sets – against Thiem, including in the French Open semi-finals a year ago.
"It’s amazing for me," Thiem said. "To beat him for the first time in the quarters of the French Open is a dream."
Plus, Djokovic had appeared in a record six consecutive semi-finals in Paris. But this continued what has become something of a 12-month downward slide for him since he finally grabbed hold of the French Open championship he had so long sought.
Since then, the highlight for Djokovic was a runner-up finish at the US Open. Otherwise, he lost his No 1-ranking to Andy Murray and lost in the third round of Wimbledon, the first round of the Rio de Janeiro Olympics and the second round of the Australian Open.
Along the way, he split with his coaches – first Boris Becker then Marian Vajda, along with other members of his entourage.
Djokovic enlisted Andre Agassi for coaching help during Week 1 of the French Open, but Agassi had some prior commitments and so was gone by the time Djokovic faced Thiem.
Thiem, 23, will face nine-time French Open champion Rafael Nadal next.
"You have to play the best guys round after round," Thiem said.
"It’s not getting easier on Friday."
The other men’s quarter-finals scheduled for later on Wednesday: 2016 runner-up Murray against No 8 Kei Nishikori, and 2015 champion Stan Wawrinka against No 7 Marin Cilic.
Thiem is a talented, up-and-coming player, to be sure, and he is the only man to beat Nadal in the Spaniard’s 23 matches on clay in 2017. That came in the quarter-finals of the Italian Open last month.
Earlier Wednesday, Nadal reached his record 10th French Open semi-final when No 20 Pablo Carreno Busta of Spain retired from their match early in the second set because of an injured abdominal muscle he said began bothering him on a serve at 5-2 in the first.
Nadal led 6-2, 2-0 when Carreno Busta stopped.
Nadal has dropped only 22 games so far in the tournament, the fewest he has lost on the way to any of his 26 major semi-final berths.
"I don’t know how many games I lost this year, but I really don’t care about this, no?" Nadal said. "I only care that I am in the semi-finals."
World No 1 Andy Murray advanced to his fifth French Open semi-final by defeating Japanese eighth seed Kei Nishikori 2-6, 6-1, 7-6, 6-1.
Murray, who was runner-up to Djokovic at Roland Garros last year, will meet 2015 champion Stan Wawrinka for a spot in Sunday’s final.
Nishikori outdueled Murray in a five-set classic at last year’s US Open and looked capable of a repeat success as he rolled through the opening set.
But Murray responded by taking the second set with ease and stormed through a third-set tie-break before finishing off a tiring Nishikori to seal a fourth successive semi-final appearance in Paris.
"I needed to start putting more pace on my shots, he was dictating all the points in the first set. It was windy, so the timing was difficult, but once I was able to get into a rhythm and keep him away from the baseline, that made the difference," Murray said.
Wawrinka became the oldest French Open semi-finalist in 32 years when he brushed aside Marin Cilic 6-3, 6-3, 6-1.
Swiss third seed Wawrinka, the 2015 title winner, has not lost a set on his way to a third successive semi-final in Paris.
The 32-year-old is the oldest man to make the last four at Roland Garros since Jimmy Connors in 1985.
"It was perfect today, I’m very satisfied," said Wawrinka, who will be playing in his third successive Roland Garros semi-final.
"I played well, was very solid and took my opportunities."
On the women’s side, Simona Halep saved a match point and fought back from a set and 5-1 down to defeat Elina Svitolina 3-6, 7-6, 6-0 to reach her second French Open semi-final.
The third-seeded Romanian, who was runner-up to Maria Sharapova in Paris in 2014, will face Karolina Pliskova, the Czech second seed, for a place in Saturday’s final.
Both women also have a chance of taking the world number one spot.
"I don’t know how I came back," admitted 25-year-old Halep, who ran away with 12 of the last 13 games to avenge her loss to Svitolina in the Rome final.
Fifth seed Svitolina had looked well-set to become the first Ukrainian woman to make a grand slam semi-final.
She allowed Halep just four winners in the first set and coasted into a 5-1 lead in the second.
Twice she served for victory at 5-2 and 5-4 before going on to waste a match point at 6/5 in the tie-breaker.
Halep needed no second invitation, sprinting through the final set in just 20 minutes before taking victory with an ace.
Svitolina, who had been two points from defeat in the fourth round against Petra Martic, finished the quarter-final with 45 unforced errors.
"She was playing tough, hard and strong," Halep said.
"Maybe I was a little lucky but I didn’t give up."
Czech second seed Pliskova reached the semi-finals for the first time with a 7-6, 6-4 win over home hope Caroline Garcia.
The Czech edged a marathon 77-minute first set against 28th seed Garcia in a tie-break, having failed to convert an earlier set point at 5-3.
The 25-year-old then broke Garcia as the Frenchwoman served to stay in the match to clinch just her second semi-final appearance at a grand slam.
"It was very tough. She played very well, we were both serving well. She played a great tournament, even today, it was 50-50, it came down to about two points I’m really glad I made it," Pliskova said.
She entered this year’s Roland Garros with just two wins in five previous visits.
"I am very happy. Before the tournament I wasn’t sure if I could play good tennis on clay."
Pliskova, 25, will replace Angelique Kerber as the new women’s world No 1 if she makes the final in Paris.
* Agencies
sports@thenational.ae
Follow us on Twitter @NatSportUAE
Like us on Facebook at facebook.com/TheNationalSport