Murray was heard speaking to the chair umpire during the match where he was complaining about the length of time Tsitsipas was off the court.
Coco Gauff survived a scare before going past Magda Linette with a 5-7, 6-3, 6-4 victory at the US Open.
Andy Murray lost in the first round of the US Open 2021 with a five-set loss to Stefanos Tsitsipas.
Osaka has had a lot of wins, which include her win at the US and Australian Open wins and a first-round win at this year's French Open before withdrawing over mental health issues.
Coco Gauff survived a scare before going past Magda Linette with a 5-7, 6-3, 6-4 victory at the US Open on Monday.
Novak Djokovic is seeded number 1 in the US Open and, unsurprisingly, is the strongest favourite to win the crown at the Flushing Meadows.
Naomi Osaka and Ashleigh Barty are the two pre-tournament favourites for the US Open. But the women's singles field is a crowded one this year.
Pablo Carreno Busta defeated Novak Djokovic in the US Open 2020 and the Tokyo Olympics bronze medal match.
Roger Federer won 41 consecutive matches in the US Open during a streak of five titles from 2004 to 2008.
The US Open has seen fewer streaks of dominance from the likes of Roger Federer, Novak Djokovic and Rafael Nadal.