US Open up for grabs after surprising year in women's tennis

Opportunity knocks at the U.S. Open as the final Grand Slam of the year rolls into New York after a season full of surprises on the women's side of the game.

The year began with world number one Ash Barty's stunning decision to retire after winning her home Australian Open in January and will end with 23-time Grand Slam champion Serena Williams joining her on the sidelines.

Barty's exit from the sport created a vacuum that was quickly filled by Iga Swiatek as the 21-year-old Pole rose to number one in March and dropped just one set en route to her second French Open title in June.

Swiatek's 37-match winning streak was finally snapped in the third round of Wimbledon and she has struggled to regain momentum since, going 4-4 in her last eight matches. Despite that she will still be the favourite in New York.

Swiatek also recently made headlines for sharply criticising the Wilson U.S. Open tennis ball, which is lighter than the ball the men use at the hardcourt major and its big tune-up events, calling it "horrible."

With Swiatek finally looking human, players like hard-hitting American Madison Keys, who notched her first win over a world number one when she defeated the Pole at the Cincinnati Open, look poised for a breakthrough.

Playing with a confidence that has at times eluded her, the tournament's 2017 finalist also beat reigning Wimbledon champion Elena Rybakina in Cincinnati and has an excellent shot at going deep again this year.

DANGEROUS OSAKA

Twice U.S. Open champion Naomi Osaka might be the hardest player to pin down at the moment.

The former world number one withdrew ahead of Wimbledon with an Achilles injury and has suffered first round exits at her last two U.S. Open tune-up events, falling to 44 in the world.