FOX Sports' Jay Glazer reported the investigation early Sunday via Twitter. Glazer's report indicates that the substance is similar to the Stick-em used to help players hold on to the ball.
The Chargers led the Broncos early in the Monday night game, but quarterback Peyton Manning and the Broncos completed a comeback of historic proportions, erasing a 24-point lead and beating San Diego, 35-24, in the Week 6 finale.
The NFL banned the substance in 1981 for its ability to help receivers catch and hold on to the ball. The rule was famously nicknamed for Lester Hayes and Fred Biletnikoff, who were notorious for using substances to achieve a better grip on the ball. Hayes was especially noted for using the substance on his arms and hands during his playing time.