Novak Djokovic crashed out of the French Open and then cast doubt over whether he will play at Wimbledon.
The 12-time grand slam winner was stunned in the quarter-finals at Roland Garros by world No.72 Marco Cecchinato.
Italian Cecchinato won in four sets, scrambling over the line in an epic tiebreak on his fourth match point.
Afterwards a dazed Djokovic, who has struggled with injury for much of the last year, was asked when he planned to make his first grass-court appearance.
He replied: "I don't know. I don't know if I'm going to play on grass. I don't know. I don't know what I'm going to do. I just came from the court. Sorry, guys, I can't give you that answer. I cannot give you any answer.
"How do I regroup? I don't know. I'm just not thinking about tennis at the moment."
The Serbian needed lengthy treatment on a neck problem after dropping the first set.
But Cecchinato proved an even bigger pain in the neck for the 2016 Paris champion.
He was mixing things up to great effect, tying Djokovic to the baseline while throwing in regular, at times remarkable, spin-heavy drop-shots from the back of the court.
Djokovic somehow regrouped to win the third set at a canter, and a suddenly frustrated Cecchinato was hit with a point penalty.
The storm seemed to have blown itself out and Djokovic served for the set at 5-3.
But from somewhere Cecchinato got a second wind and took the fourth in a thrilling tie-break, converting a fourth match point to win 6-3 7-6 (7-4) 1-6 7-6 (13-11).
Cecchinato had not won a single grand slam match until he arrived at Roland Garros, but the 25-year-old is now the first Italian to reach the semi-final since Corrado Barazzutti 40 years ago.
He said: "Maybe I'm sleeping. It's amazing. It's unbelievable for me. For me to beat Djokovic in a quarter-final at Roland Garros it's amazing.
"For me, it's the first time semi-final grand slam. Now I need to think for the semi-final and I need some rest for recovery. I am very happy."
Cecchinato will meet Dominic Thiem in the semi-finals after the Austrian eased past Alexander Zverev 6-4 6-2 6-1, while Sloane Stephens and Madison Keys both won to set up an all-American women's semi-final.