Video replays were used for the first time to send off a player for a professional foul in a Major League Soccer reserve match.
The technology is being trialled at New York Red Bulls' stadium, with a video assistant referee taking 30 seconds to review a challenge in a Red Bulls II match against Orlando City.
A screen at the side of the pitch helped the officials decide to dismiss Orlando's Conor Donovan for denying a goalscoring opportunity just outside the penalty area.
Video replays will be used to advise on "game-changing" decisions in United Soccer League matches - the third tier of US football. That includes goals, red cards, mistaken identities and penalties.
They will also be tested in six other countries in the next two years, including Germany and Italy.
The game's lawmakers, the International Football Association Board (IFAB), wants to decide by 2019 on whether to introduce video replays across the sport.