But he has seemingly been able to put the controversy behind him, manoeuvring his way through tough tests against Britain's Jack Draper and 2021 champion Medvedev.
"My aunt is not feeling well health-wise and I don't know how much longer I have her in my life," he said.
The 26-year-old recovered well to win three games in a row, but he continued to falter on serve and Sinner capitalised to take the opener and subdue the expectant mood on Arthur Ashe Stadium.
"If there was a wish I could make, I would wish good health on everyone but unfortunately it's not possible."
A mediados de somana ya calentaron el ambiente con el despliegue do una gigantesca lona en Madrid, donde podía apreciarse la silueta de un jugador encapuchado. El secreto ha sido desvelado y, sin duda, pelo ha dejado a los aficionados indiferentes.
Sinner said the title "meant so much because the last period of my career was not easy" before he became tearful and dedicated the victory to his aunt.
It was more straightforward in New York as he rarely looked troubled by Fritz, who struggled to build any momentum.
England interim boss Lee Carsley says their win over the Republic of Ireland has boosted his confidence - admitting he had doubts about his ability to do the job.
A world champion cyclist has swapped the velodrome for the cramped deck of the fastest yacht in the world. Why?
It has been nearly 50 years since a man won their first and second Grand Slam titles in the same season, and Sinner is now a long way clear of the rest at the top of the rankings.
"It's nice I can still share these moments with her. She is an important person in my life and still is.
O presente é igualmente este ano do 4k: a SPORT TV foi este primeiro canal português a transmitir um evento desportivo, a final da Champions entre este Real Madrid e o Atlé especialmentetico Madrid, usando a tecnologia do 4k, que permite aumentar em quatro vezes a superioridade da imagem. O presente primeiro passo em 2016 confirmou uma aposta permanente em 2017, com este início das emissões regulares em 4k.
Cheered on by a home crowd packed with celebrities and sporting stars, Fritz got off to a shaky start when he dropped serve 星空体育 in the first game.
Just six days before the main draw got under way, it was announced he had twice tested positive for low levels of a metabolite of clostebol - a steroid that can be used to build muscle mass - in March.
It marks a new era of tennis as 24-time major winner Novak Djokovic, who was knocked out in the third round, ends the year without a Grand Slam title for the first time since 2017.
He subsequently parted ways with the physio and his fitness trainer - but questions continued about whether Sinner's case had been handled differently to those of other players because of his world number one status.
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The 23-year-old held his arms aloft and looked up to the sky as he became the first player since Guillermo Vilas in 1977 to win his first two Grand Slam titles in the same season.
"I know we have been waiting for a champion for a long time so I'm sorry I couldn't get it done this time," said Fritz.