Britain's Andy Murray says there must be "severe repercussions" for players who break the US Open safety bubble at next month's Grand Slam in New York.
The event is set to be held without fans at Flushing Meadows with players having to follow strict measures.
But there are fears some may break the curfew by going out in Manhattan and putting the event in jeopardy.
"The repercussions should be quite serious, you end up putting the whole tour and event at risk," said Murray.
The United States Tennis Association is hosting a double tournament at Flushing Meadows, having moved the Cincinnati Masters to New York.