Serena Williams was fined $10,000 on Sunday for her tirade against a line judge at the conclusion of her loss in the semifinals of the United States Open on Saturday, and may face more penalties, including a possible suspension from next year’s Open. Williams, who has already earned $455,000 for singles and doubles at this tournament, was fined $10,000 for unsportsmanlike conduct and $500 for racket abuse, which occurred earlier in the match, by the tournament referee, Brian Earley. The $10,000 was the maximum fine that could be levied on site.