Novak Djokovic admitted that the medical effects of being struck in the head by a bottle played a role in his third round loss in the Italian Open on Sunday and said he felt like a "different player" on court.
The 24-time Grand Slam champion put on one of his worst displays at one of his favorite tournaments as he was upset by 29th-seeded Alejandro Tabilo.
It was Djokovic's first match since accidentally getting knocked on the head by a water bottle while signing autographs after his opening round win on Friday.
"That has really impacted me a lot. After that I got medical care, been through half an hour, an hour of nausea, dizziness and blood," Djokovic said at a news conference, adding that he would go for scans later. "I managed to sleep OK. I had headaches. The next day, or yesterday, was pretty fine, so I thought it's OK. Maybe it is OK, maybe it's not.
"The way I felt on the court today was just completely like a different player entered into my shoes. Just no rhythm, no tempo, no balance whatsoever on any shot. It's a bit concerning."
Djokovic started off with a double fault, and it didn't get much better for the six-time Rome champion.
The top-ranked Djokovic lost his first two service games and went on to lose the match 6-2, 6-3 in just 68 minutes, handing Tabilo the victory when he double-faulted -- his fifth of the match -- amid boos at the Foro Italico.
"I'm trying to soak it all in and wake up right now," Tabilo said after the biggest win of his career. "I was just trying to keep my nerves in and keep swinging. Towards the end my arms were getting tired but I was trying not to think about it.
"It's crazy, I just can't believe what's happened. I can't believe it right now. I don't think anyone can believe it."
The third-round loss marked Djokovic's worst performance at the Italian Open. He had lost only once before to an opponent outside the top 10 in Rome, where he had never gone out before the quarterfinals.
Djokovic followed Rafael Nadal to an early exit after the record 10-time Rome champion lost his third-round match to Hubert Hurkacz 6-1, 6-3 on Saturday.
While Djokovic had said he was "fine" after the water bottle incident, it was an unusually off-key performance from the Serb as he tries to step up his game on clay before attempting to defend his title at the French Open, which starts May 26.
"I was going for kind of easy training yesterday. I didn't feel anything, but I also didn't feel the same," Djokovic said.
"Today under high stress, it was quite bad -- not in terms of pain, but in terms of this balance. Just no coordination. Completely different player from two nights ago. ... I don't know. I have to do medical checkups and see what's going on."
Djokovic had 12 unforced errors to Tabilo's four and produced 14 winners to his opponent's 22. It was also a rare occasion when he had zero break point chances.
He was broken four times in the match, including in the final game, and Djokovic could only shake his head when another unforced error handed Tabilo match point.
Djokovic is still without a title this year -- the first time he's reached May without a trophy since 2018, when he was returning from a right elbow injury.
Tabilo next faces 16th-seeded Karen Khachanov, who beat Francisco Cerundolo 6-2, 6-4.
Third-seeded Alexander Zverev advanced after the 2017 Rome champion beat Luciano Darderi of Italy 7-6 (3), 6-2. Grigor Dimitrov and Thiago Monteiro also advanced, while Taylor Fritz beat American compatriot Sebastian Korda 6-3, 6-4. Another American, Ben Shelton, lost to Zhang Zhizhen.
In the women's tournament, second-seeded Aryna Sabalenka eased through to the fourth round with a 6-4, 6-2 win over Dayana Yastremska.
American Sofia Kenin, who won the Australian Open in 2020 and also reached the final at Roland Garros the same year, was upset by Slovakian qualifier Rebecca Sramkova 6-4, 4-6, 6-4.
American Danielle Collins is safely through after beating Caroline Garcia 6-3, 6-3. Also advancing in third-round matches were Maria Sakkari, Irina-Camelia Begu, Jelena Ostapenko, Victoria Azarenka and Elina Svitolina.
The Associated Press and Reuters contributed to this report.