Mike Tirico and Jon Gruden break down Michael Vick's performance on Monday Night Football to guide the Steelers past the Chargers. (1:17)

The Pittsburgh Steelers won a thriller on Monday Night Football by getting a touchdown from running back Le'Veon Bell on the game's final play from scrimmage for a 24-20 victory over the San Diego Chargers.

Had Bell not scored on that play, however, the NFL would have had another wild controversy on its hands. For reasons that were not immediately clear, 18 seconds ran off the game clock after a touchback at the start of the Steelers' final possession.

The rundown was visible on ESPN's broadcast graphic, as well as a shot of the Qualcomm Stadium scoreboard as Steelers quarterback Mike Vick jogged onto the field. It was also revealed in the game's official box score, in the possession time and in the time of the Steelers' first play from scrimmage for that series.

Steelers coach Mike Tomlin said he wasn't aware of the clock error.

"Didn't change the outcome of the game," he said.

NFL spokesman Brian McCarthy told ProFootballTalk.com that the league is reviewing the situation and expects to address it soon.

Instead of taking over with 2:56 remaining, the Steelers got the ball with 2:38 left. Bell's winning touchdown came with no time remaining on the clock.

Per the NFL's public operations website, the side judge is responsible for backing up the stadium clock operator and keeping time on the field if the clock malfunctions. Ultimately, referee Pete Morelli is responsible for all on-the-field action during a game.

Information from ESPN Staff Writer Jeremy Fowler was used in this report.