The world number one player typically rides into Flushing Meadows on a wave of positive headlines, basking in a US Open spotlight that shines brighter than the Times Square billboards.
Instead, Italian Sinner spent the lead-up to New York tamping down injury concerns and on Tuesday became embroiled in controversy after the International Tennis Integrity Agency said that he tested positive twice for an anabolic agent in March.
An independent tribunal convened by Sport Resolutions accepted his claim that the positive tests were the result of contamination, clearing him of wrongdoing, after Sinner maintained his innocence.
"I will now put this challenging and deeply unfortunate period behind me," he wrote on the social media platform X.
Seven-time major winner and ESPN analyst John McEnroe called the news - and its timing - "surprising and shocking," while some of Sinner's fellow players cried foul.
"Can't imagine what every other player that got banned for contaminated substances is feeling right now," said Canadian Denis Shapovalov.
The saga marks the latest dip in a rollercoaster 2024 for Sinner, who started the year on a high by picking up his maiden major in Australia before winning in Miami but saw his season shortened due to a hip issue he picked up in May.
The injury forced him to pull out of Madrid before his quarter-final and to miss Rome entirely. He also backed out of the Olympics due to tonsillitis.
Sinner on Monday showed he could still find some form as he beat American Frances Tiafoe in Cincinnati, a key US Open tune-up event, despite limping around the court on several occasions in the first set.
The Italian will hope to find his best level in New York if he runs into top contenders including Spanish rival Carlos Alcaraz and newly-crowned Olympic champion Novak Djokovic, who will be in search of a record 25th Grand Slam title.
The US Open main draw begins on Monday.