Today in U.S. Open: Djokovic, Cilic and Serena vs. Venus

9-8-15 Serena Williams
Serena Williams of the U.S. serves to compatriot Madison Keys during their fourth round match at the U.S. Open Championships tennis tournament in New York, September 6, 2015. She faces her sister, Venus, in the quarterfinals Tuesday. Adrees Latif/Reuters

Tuesday marks the ninth day of play for this year's U.S. Open, and the start of the quarterfinals matches across singles and doubles categories. In other words, the heat is on, both figuratively and literally, with a high of 93 degrees forecast Tuesday for Flushing Meadows-Corona Park Queens, New York, home to the USTA Billie Jean King Tennis Center.

Monday saw No. 2 seed Roger Federer of Switzerland defeat John Isner of the U.S. to snag a familiar spot in the quarterfinals. But third seed Andy Murray—who has reached the quarterfinals in each of the 18 major tournaments he's played since 2011 and won the U.S. Open in 2012—exited the tournament when he lost to Kevin Anderson of South Africa during a match that lasted more than four hours. This was a surprise win for Anderson, the No. 15 seed who has competed in more than two dozen major tournaments since 2008 but never reached the quarterfinals.

The results of Monday's games mean that Victoria Azarenka of Belarus, Flavia Pennetta of Italy, Simona Halep of Romania and Petra Kvitova of the Czech Republic have advanced to the women's quarterfinals, while Federer and Stan Wawrinka of Switzerland and Richard Gasquet of France join Anderson in advancing to the men's quarterfinals.

Singles games begin at noon on Tuesday with Kristina Mladenovic of France facing Roberta Vinci of Italy and Jo-Wilfried Tsonga of France playing Marin Cilic of Croatia at the Arthur Ashe Stadium.

The excitement rises in the evening for what some are calling the match of the day: sisters Venus and Serena Williams battling one another to advance to the semifinals. Younger by 15 months, Serena is three matches away from a calendar grand slam. In other words, if she makes it to the finals of the U.S. Open and wins the tournament, she'll be the first to win all four major annual tournaments in one year since Steffi Graf in 1988.

Finally in the men's singles tournament, No. 1 seed Novak Djokovic of Serbia—who won a tough match Sunday against Spain's Roberto Bautista Agut to advance to his 26th consecutive grand slam quarterfinal—will face Feliciano Lopez, also from Spain.

Fans can check the schedule for singles, doubles and juniors matches online, and can watch Tuesday's matches on ESPN or ESPN3, sign in to stream the games online or track scores live online.