The athlete entered the previous US Open as the 26th seed.
The tennis professional disclosed he pondered ending his career due to debilitating back issues during the season.
The 27-year-old, who has reached a career-high ranking of world number three, finished as runner-up against Novak Djokovic at both the 2021 French Open and the 2023 Australian Open.
Now ranked as the world's 36th best player following minimal competition post a early exit at the US Open in August, he stated continuous medical care has begun yielding positive results.
"My greatest anticipation is to observe how my training holds up under actual training with regard to my back," said Tsitsipas.
"The biggest fear centered on if I could complete a match," he added, noting the injury plagued him "for the past half a year or more."
"I would wonder, 'Am I able to play another contest without discomfort?'"
"I became truly frightened after the defeat in Flushing Meadows [to Germany's Daniel Altmaier]. I could not to walk for 48 hours. That's when you begin to question your career's future."
Tsitsipas further mentioned being content with his current recovery plan after finishing five weeks of off-season preparation completely pain-free.
His next appearance for Greece at the team event, drawn against Team Japan led by Osaka and the British team captained by Raducanu. The competition takes place across Australian cities from 2 to 11 January, just before the season's first major.
"My main goal for 2026 would be to stop worrying over completing bouts," he stated.
"It provides fantastic feedback to know you completed an off-season without pain – I hope it continues. I want to deliver during the upcoming season and for the United Cup.
"I have done the work. The most important thing is total belief that I can return to my previous level. I will try all means to make it happen."
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