WUHAN, CHINA - SEPTEMBER 30: Ashleigh Barty plays a backhand during the ladies singles final between Ashleigh Barty of Australia and Caroline Garcia of France during Day 7of 2017 Dongfeng Motor Wuhan Open at Optics Valley International Tennis Center on September 30, 2017 in Wuhan, China. (Photo by Yifan Ding/Getty Images)

Week 1 of the US Open produced a high level of tennis, some predictable results, and some big upsets.

The women's side of the draw lost the first and third seeds, while a young Greek star was toppled after a dramatic week. Looking through the chaos, here are the five biggest upsets from week one.

Ash Barty vs Shelby Rogers 
The world number one was in fine form when she arrived in New York. The Australian won her first Wimbledon title in July followed by an impressive run in Cincinnati earning the 25-year-old her fifth trophy of the season, leaving Barty one of the heavy favourites to claim her third grand slam win at the US Open.

Barty's quest was cut short against home town favourite Rogers, who played inspired tennis to take down the world number one in three sets. Barty led 5-2 in the third, before Rogers fought back to bring the set to a tiebreak finish, eventually claiming the win 6-2 2-6 7-6. The New York crowd was electric, spurring Rogers home in a memorable night for the American and the fans, but a forgettable one for the Australian.

Stefanos Tsitsipas vs Carlos Alcaraz
Known as the "next Rafa" in his native Spain, Alcaraz is making a name for himself at this years tournament. At just 18 years old, Alcaraz is the youngest player in the Open Era to reach the quarterfinals at the US Open, to do so, he had to get past the world number three.

Tsitsipas escaped victorious from a close opening round match against Andy Murray, which generated drama that seemed to follow the young Greek star for the remaining of his US Open campaign.

His often long bathroom breaks at crucial moments made him the villain of the New York crowd, who cheered on Alcaraz in their five-set thriller. Tsitsipas dropped the first set before regaining composure in the second, eventually losing 7-5 in a nail-biting fifth set tiebreak.

The 18-year-old Spaniard is now one win away from making the semi finals of a grand slam, while French Open finalist Tsitsipas reflects on a gruelling match while dodging questions from the press and his peers about his bathroom habits.

Naomi Osaka vs Leylah Fernandez 
Osaka's grand slam return after missing Wimbledon for personal reasons hit a road bump when facing lively Canadian qualifier Fernandez. Osaka, who had little match practice heading into the US Open, had few answers when facing the 19-year-old Canadian who has been on a giant killing streak in New York.

Osaka was visibly frustrated as Fernandez excelled, eventually claiming the 7-5, 6-7 (7-2), 6-4 victory. At one point Osaka threw her racquet in frustration after several errors, while her teenage counterpart remained cool under pressure on her side of the net. Following her win against Osaka, Fernandez defeated grand slam champion Angelique Kerber in three sets, she now faces a quarter final match against Elina Svitolina, a day after she celebrated her 19th birthday.

Diego Schwartzman vs Botic Van de Zandschulp

Despite being one of the shortest players on tour, Schwartzman is able to play a big game, earning him the 11th seed at this years US Open. The Argentinian's fourth-round opponent, Van de Zandschulp, hasn't had the same success in his career but pulled off an unbelievable win in a five set epic.

The Dutch qualifier had never stepped foot inside the United States before this years open and found himself playing in Louis Armstrong Stadium for one of the matches of the tournament, lasting a whopping 4 hours and 20 minutes. Van de Zandschulp is a little known name on tour, he has a career-high ranking of 117 and before New York, had never progressed past the second round in a grand slam.

The 25-year-old is now facing world number two Daniil Medvedev in the quarterfinals on the biggest tennis stadium in the world, should he replicate his fourth round brilliance, he could pull off one of the upsets of the year.

Reilly Opelka vs Lloyd Harris 
While Opelka may not generate the same recognition as his high ranking peers, the American has been putting together a solid season, including two back-to-back finals appearances in Canada and Cincinnati.

The 22nd seed was a quiet underdog going into Flushing Meadows, where South African Lloyd Harris ended his tournament early in the fourth round. 24-year-old Harris has been a quiet achiever during his time on tour, making the fourth round against Opelka for the first time in his career.

The two met in Toronto, where Opelka went on to claim the title, but Harris got the win this time, booking in a match up against Alexander Zverev in the quarterfinals. It's not the first upset Harris has pulled off this year, managing to topple Dominic Thiem in Dubai, while he also had a strong run at the Australian Open.