ITF officials Monday said the fine would be reduced to $82,500 if Williams commits no additional offenses before 2011 but another offense in the next two years would bar her from the following U.S. Open.
Even the $82,500 fine would be an ITF record for a Grand Slam event, far surpassing the $48,000 fine levied against Jeff Tarango at Wimbledon in 1995.
Williams, who ended the WTA season with a world No. 1 ranking, confronted a line judge who called Williams for a foot fault in the U.S. Open semifinals against Kim Clijsters.
Williams trailed 4-6, 5-6 and the foot fault call made the score 15-40, putting Clijsters one point from the finals. Williams gestured at the line judge. Court-side microphones picked up Williams saying she would -- if she could -- shove a tennis ball down the judge's throat. There were several expletives from the player.
The official reported the incident to the chair umpire, who, since Williams had been warned previously for destroying a racket, docked her one point, which ended the match.
After the match, Williams said: "I didn't threaten (the line judge). I don't remember anymore, to be honest. I was in the moment. And, you know, everyone's fighting for every point. It was a really crucial point."