The NFL is warning teams about faking injuries and threatening stiff penalties for a practice it discourages, but has never proposed a specific rule to outlaw.
In a memo sent to teams on Wednesday, the NFL said faking injuries to gain a timeout without incurring a penalty could be subject to fines, suspensions or forfeiture of draft picks.
The notice came after Giants safety Deon Grant, a 12-year veteran, was accused of faking an injury as the Rams were driving in a no-huddle offense during the first quarter of Monday night's game.
As the Giants struggled to get personnel on and off the field, Grant and another player, linebacker Jacquian Williams, dropped to the ground, forcing a whistle and preventing the Rams from hiking the ball.
Williams got up quickly, but Grant remained on the ground as an injury timeout was called.
Afterward, Rams head coach Steve Spagnuolo notified the NFL he thought the Giants were faking injuries. The coach said Tuesday that he couldn't fault the referees.
"They can't make the decision if somebody is hurt or not hurt," said Spagnuolo. "You just don't know that."
Giants head coach Tom Coughlin said he thought Grant was cramping up, but the league clearly saw enough of a reason to issue a warning against the practice.
The NFL memo, obtained by ESPN and posted online, is addressed to team presidents, general managers, head coaches and public relations executives.
After reminding the teams of a league policy discouraging the practice, the memo explains that the NFL has been reluctant to propose a specific rule governing the practice over fears that teams will lose legitimate timeouts or injured players will be encouraged to remain on the field.
"To avoid the necessity of a rule with many unattractive qualities, teams are strongly urged to cooperate with this policy," the memo says.
"We have been fortunate that teams and players have consistently complied with the spirit of the rule over the years and this has not been an issue for the NFL. We are determined to take all necessary steps to ensure that it does not become an issue."
If there is reasonable cause to believe the policy is being violated, the NFL said it would summon anyone involved to the league office in New York City to discuss the matter.
"Those found to be violators will be subject to appropriate disciplinary action for conduct detrimental to the game. Discipline could include fines of coaches, players, and clubs, suspensions or forfeiture of draft choices," the memo says.