Here we go again.

First, it was that dress and then the runners, and now it’s all about tennis balls. The optical illusion that has everyone on Twitter going mad right now is all about those fluorescent balls and we're totally thrown. It’s been a point of contention for years, however, Deadspin recently revived the debate by simply asking one question: “What colour are tennis balls?” A question we never knew we needed to ask is now the question we need answers to immediately. And we’re not the only ones – it seems like everyone on Twitter is torn when it comes to a decision on this.

Truly had no idea this was ever in question. https://t.co/nAkmbpV4hP

— Alexis Levinson (@alexis_levinson) March 20, 2018

Yellow. Wait no green. Wait no yellow.

Ugh. Harder than I thought. Touché. — Ryan Heckman (@ryanmheckman) March 20, 2018

lol omg thats hilarious.. and yep theyr definitely yellow ??✨ pic.twitter.com/E6BZw7Tudl

— narelle (@ensquaredx2) March 19, 2018

pic.twitter.com/r7bVSbzwCW

— Adam Beilman (@AdamBeilman) March 20, 2018

pic.twitter.com/UjY76KfUBH

— 30andexhausted (@romasfinest05) March 20, 2018

It’s not just your ordinary Joe Soaps either, even professional tennis players are not fully confident in their answers.

OKAY ITS OFFICIAL MY DAD JUST ASKED @rogerfederer IF TENNIS BALLS ARE YELLOW OR GREEN AND HE SAID THEY ARE YELLOW pic.twitter.com/EXdXRr0oFa

— Delaney Dold (@delaneyanndold) March 19, 2018

Tennis balls are green. Why is this a question. Roger Federer is wrong. https://t.co/R93wElqjAq

— Audra (@audra_spiven) March 20, 2018

if roger says they're yellow, theyr yellow ?? pic.twitter.com/anh3Hb8tWl

— narelle (@ensquaredx2) March 19, 2018

I would have said green but I think we have to all have to agree on yellow now. https://t.co/4DupnjuWRF

— corey (@chendizzle) March 20, 2018

If this is all reminding your of that dress, you’re not the only one but apparently, your thoughts on that could be at play again here as someone says whatever colours you saw there are linked the colour you think a tennis ball is.

Are ? yellow or green? @rogerfederer, please help. https://t.co/1kdKQfyTiS pic.twitter.com/VJa7hZDufj

— David Bauer (@davidbauer) February 24, 2018

So, what is it you see - green or yellow?