Serena Williams "went too far" with her controversial rant at an umpire during the US Open final, according to Roger Federer. Williams received a code violation for coaching, a penalty point for racquet abuse and a game penalty for calling the umpire a "liar" and a "thief" during her defeat by Naomi Osaka, with her outburst overshadowing the biggest win of her opponent's career.

"I feel like Serena should have walked away," Federer told Britain's Sunday Times newspaper. "She did, but she went too far. She should have walked earlier." Nevertheless the Swiss star did have some sympathy for Williams, adding: "The umpire maybe should not have pushed her there. It's unfortunate, but an incredible case study." Osaka's 6-2, 6-4 win over Williams quickly became infamous for the American's flare-up in the second set.