It’s one of the biggest questions that has puzzled the tennis world for years now.

What colour is a tennis ball exactly?

You may remember "The Dress" debate from a few years back that was deemed white and gold by some, while other portions of the population deemed it was blue and black

The great colour debate now has moved into the sporting world, and one of the best tennis players in the history of the sport chimed in with his thoughts on if a tennis ball is actually green or yellow.

There you have it. According to Feds, the ball is yellow. But is it actually, though? Thanks to the fine folks over at For the Win, we have the most realistic answer on the subject from a colour expert.

“Asking if a tennis ball is one color or the other, yellow or green, is like having to decide if the ocean is green or blue,” according to Behr paint color expert Erika Woelfel. “With color, it doesn’t always have to be such a simple answer. In this case, it’s both! Or, as we like to call it: chartreuse.”

So, what do you think, or maybe the better question is, what is your brain trying to tell you that your eyes may disagree with? Everyone's eyesight will see something different.

Is it a blend of both, or do you see yellow or green? You can weigh in on this Twitter poll here and see you’re a part of the majority or not.

(h/t For the Win)