-- NEW YORK -- After falling short at the Rio Olympics, Serena Williams?returns to the court at the US Open. The world No. 1 will be featured in Arthur Ashe Stadium in Tuesday's first night match ( 7 p.m. ET on ESPN). While Serena will headline Day 2, here's everything else you need to know:
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Tuesday's key matches
Hard to imagine Venus, 36, would still be viable on tour 16 years after winning her first US Open -- never mind being the No. 6 seed. It's been a roller coaster of results for Venus, who reached the semifinals of Wimbledon last month but then fell in the opening round of Rio in singles and doubles with sister Serena. However, Venus teamed with Rajeev Ram and reached the mixed-doubles final. On Tuesday, Venus, who made the US Open quarterfinals last year, will meet Kozlova for the first time.
Fresh off a magical Rio run, del Potro has to be the most dangerous unseeded player in the draw. The 6-foot-6 Argentine stunned Novak Djokovic and Rafael Nadal at the Olympics, only to lose a hair-raising four-set final against Andy Murray. Del Potro, who made it clear that his goal was nothing more than to be able to play pain-free in Rio, won the 2009 US Open. Since then, he has undergone four wrist surgeries and has missed more than two years' worth of action. No question, del Potro will be a sentimental favorite here in New York.
All eyes will be on the world No. 1, who will be vying to break a tie with Steffi Graf as the Open era leader in Grand Slam titles. But there are concerns over Serena's level of play and health as she enters the final major of the season. She lost in the third round of the Olympics to Elina Svitolina and then pulled out of the Western & Southern Open with an ongoing shoulder injury. Serena is 4-1 lifetime against Makarova, including two wins against the Russian at the US Open.
The red-hot Scot will be riding the momentum of his Wimbledon and Rio titles into New York. Murray won 24 straight matches, a streak that was stopped in the Cincinnati final by Marin Cilic. Still, Murray is rife with confidence, and many believe he, not defending champ Djokovic, will leave New York with the title. Murray's first opponent, however, won't be a pushover. It could also be contentious. Last season, Rosol bumped Murray on a changeover in Munich, to which Murray retorted: "No one likes you on the tour. Everyone hates you." Murray is 2-0 in his career against Rosol.
Big things have been expected from Kyrgios, 21, since he stunned Nadal at Wimbledon two years ago. The Aussie is finally showing his game can be just as loud as his antics. He's won two titles this season, including the Atlanta Open just a few weeks ago. But can he leverage his stellar play in New York? Last year, Kyrgios had the unfortunate luck of drawing Murray in the opening round. But this year, he takes the court ranked a career-high No. 16 (and seeded 14). The courts in New York suit his hard-hitting game well.