Colour-blind NFL fans expressed their frustration after being unable to distinguish between the New York Jets and Buffalo Bills on Thursday night.
Both teams were wearing the new 'Colour Rush' uniforms, with the Jets in all green and the Bills in all red as part of an experiment to spice up the viewer experience.
The NFL says the new Nike uniforms had been designed to "honour each franchise", with six more teams set to wear them in Thursday games over the remainder of the season.
It is a departure from the NFL's usual requirement for one team to wear white and one a darker uniform.
The United States National Eye Institute says as many as eight per cent of men and 0.5 per cent of women with North European ancestry suffer some form of colour blindness, with red-green colour blindness the most common form.
And the combination of Bills and Jets uniforms, on a bright green artificial turf background, left many confused, including former New York Giants kicker Lawrence Tynes.
Tynes, who was born in Scotland, wrote on Twitter: "if you are colour blind like me, this @NFL game is going to be hard to follow @buffalobills v @nyjets."
NFL.com reporter Gregg Rosenthal was in the same boat, and he wrote: "When Ryan Fitzpatrick threw his first pass of the night, it looked to me like two different Jets team-mates went for the ball.
"Then I realised all 22 players just looked like they played for the same team. The issue in the Bills' 22-17 win over the Jets was exacerbated on the green playing field, especially when the camera was far from the action during live plays. (It's less of a problem on replays)."
The next game involving 'Colour Rush' uniforms will come on Thursday when the Jacksonville Jaguars will wear almost all gold uniforms against the baby blue-clad Tennessee Tirans.