Flavio Cobolli said he was hit by cramps late in his French Open final defeat by Alexander Zverev on Sunday, as he faded in a tense fifth set.
The Italian 10th seed had treatment between the fourth and deciding sets but slipped to a 6-1, 4-6, 6-4, 6-7 (5/7), 6-1 loss as Zverev claimed his first Grand Slam title.
"I felt cramps on my calf. You know, I tried all my best on the changeover," said Cobolli.
"I took all five minutes. But my calf was gone. At the end after the second game also my quad, and I felt completely tired. My body left me on the court."
The 24-year-old was playing in his first Grand Slam final and had never even played a semifinal before after receiving a walkover on Friday when last-four opponent Matteo Arnaldi withdrew.
Cobolli appeared to struggle badly with nerves in an erratic first set, before settling into the contest as the match went on.
The 29-year-old Zverev was playing in his fourth major final after suffering three previous defeats.
"Today I felt a little bit of pressure, maybe more than him," Cobolli said.
"Also, I'm happy for how I played my first final of a Grand Slam. It's never easy to play for the first time on this stage, on these kind of matches."
Cobolli will climb into the top 10 of the ATP rankings on Monday for the first time and says he will push to reach another Slam final.
His next chance will be at Wimbledon, where he enjoyed his best previous run at a major tournament last year by reaching the quarterfinals before losing to Novak Djokovic.
"I will try and try and try, but when you reach the first final, why not the second?," he added.
"At the end, I think I deserve to be here on these weeks. Maybe not in the next 10, 15 Slams, but... I'm still young.
"So I have to work a lot, enjoy this journey, and maybe if I work and enjoy a mix of things, maybe I will reach again the final."