Williams, 40, and Federer, 41, have both announced in short succession their plans to retire, leaving the tennis world without two of its most iconic players.
Several of the players marked firsts for the sport's history, while for Serena Williams, the tournament may have been her last match.
The 23-time Grand Slam champion staved off five match points to prolong the three-hours-plus proceedings, but could not do more, and was eliminated from the U.S. Open in the third round.
Capacity crowds have turned out to watch American tennis star Serena Williams play in the first two rounds of the U.S. Open. She's said this might be her last tournament. No one wants to say goodbye.
Serena Williams says she is close to retirement. We take a look at her life and career from Compton to Wimbledon, and the impact she has had on athletes, particularly African American women.
At least one viewer watching at home thought they spotted Beyoncé in the star-studded stands at Serena Williams' U.S. Open match Monday night. Cox, who "worships" the singer, took it in stride.
The transcendent star of women's tennis delays her farewell after defeating Danka Kovinic Monday night in her opening match of the U.S. Open.
When the tennis megastar announced her plans to retire from competition last week, she said her future will involve a renewed focus on a venture capital firm she quietly founded eight years ago.
"I'm turning 41 this month, and something's got to give," Williams told Vogue. She attributed the choice to the competing urges of wanting another child while facing off with the world's best players.
King Richard is nominated for six Oscars, including Best Picture. Will Smith, Isha Price, and Aunjanue Ellis explain how faith motivated the Williams' family.