Stefanos Tsitsipas pledged Tuesday to cut out "naps and melatonin" after admitting virtually sleepwalking into a French Open defeat by Carlos Alcaraz.

The world number five from Greece slumped to a 6-2, 6-1, 7-6 (7/5) loss against top seed Alcaraz in a disappointing quarter-final.

"One thing that I'm going to try to avoid in the future is have melatonin pills and naps before matches because it clearly doesn't seem to be working," said Tsitsipas of his pre-match routine.

Melatonin in tablet form is often taken to treat sleep disorders.

Tsitsipas, the runner-up to Novak Djokovic in Paris in 2021, only woke up to the task at hand in the eighth game of the third set on Tuesday.

He saved two match points and then another in the 10th game as he pulled back from 2-5 down to 5-5 before Alcaraz eased through the tiebreak.

It was the 20-year-old Spaniard's fifth win in as many meetings with Tsitsipas.

"The schedule has been a little bit difficult the last few days. I had some late-night sessions. Not super late, but late enough for me to kind of have my sleep schedule ruined," added Tsitsipas.

He recalled a 6-1, 6-2 loss to Djokovic at the Paris Masters in 2019 when the match played out in the same way after he had had tried to catch up on sleep.

"I feel like melatonin really likes 1 and 2," he said, referring to the set outcomes.

"It wasn't really that much fun out there in the first two sets. I felt completely off, kind of like sleeping in a way. I just wish it never happens again. It sucks."

Despite his defeat, Tsitsipas hailed US Open champion Alcaraz, who will face 22-time major winner Djokovic in a blockbuster semi-final on Friday.

However, the 24-year-old Greek said he found it impossible to pick a winner.

"One has experience; the other one has legs and moves like Speedy Gonzalez," he explained.

"One can hit huge, super big shots; and the other one prefers control over anything else, probably control and precision, to apply pressure and just make the opponent move as much as possible."

bur/dj/sst