The NFL's new helmet rule got its first test on Thursday during the opening preseason game of the year.
Patrick Onwuasor was called for illegal use of helmet after leading with his head to bring down Bears running back Benny Cunningham.
The rule has caused confusion across the league, with officials and teams alike unable to clarify what is a penalty.
Football fans didn't have to wait long to see how officials would be enforcing the league's new rule regarding players that lead with their helmet.
Just over four minutes into the opening game of the 2018 preseason between the Baltimore Ravens and Chicago Bears, Ravens linebacker Patrick Onwuasor was called for illegal use of helmet after a tackle, resulting in a 15-yard penalty.
Onwuasor did not seem out of control while bringing down Bears running back Benny Cunningham. The replay showed he did put his head down ahead of contact, prompting the official to throw the flag.
You can get a look at the play below.
While the rule was put in place to make the sport safer, the use of helmet rule has thus far caused headaches for players, coaches, and officials attempting to figure out just how it will be enforced.
The rule, which bans players from lowering their helmet to initiate contact but confusingly allows for "incidental contact," has been criticised as vague by detractors, with Fox rules analyst and former NFL vice president of officiating Mike Pereira saying the rule would be "impossible to officiate."
Officials efforts to clarify the rule have reportedly fallen short — after the Philadelphia Eagles hosted referees for a presentation regarding the new rule, they were apparently left with more questions than answers.
"[The refs] were kind of like, 'Hey, we didn't make the rules.' Because I think guys were kind of frustrated," running back Wendell Smallwood said. "Most of the defense was like, 'Man, how are we supposed to tackle?' They were frustrated."
See more from the game:
Ultimately, teams will have to learn on the fly as the rule is enforced through the preseason, and adjust to the officials tendencies as necessary, and on Thursday, they got their first look at just how much the rule could affect the game.