It's not just tennis promoters...
...that screw with the fans, by sometimes delaying the release of unpleasant news (withdrawals, etc.).
For those of you that follow the NFL, you've undoubtedly heard about the surprise retirement of RB Ricky Williams. The Dolphins announced it Sunday. However, further probing revealed that Williams actually told the Dolphins he was quitting on the Friday before. So why did they wait 2 days to release this news? It seems that Saturday was the Dolphins' annual ticket drive, when they sell the bulk of their season tickets and other packages. They obviously figured they wouldn't sell as many if the fans knew the Dolphins would be missing their star player.