One of the biggest questions to be Emmanuelle – The Sex Lives Of Ghosts (2004)posed in modern history isn't "is the dress blue/black or gold/white?" It's something much, much more complex and nuanced:

Are tennis balls green, or are they yellow?

It's been debated in Slack channels, social media feeds, and probably in tennis courts, but until today and to my knowledge, there has not been an official declaration of color from any current ranking tennis champions themselves. Thank goodness Roger Federer has put an end to that.

While in Chicago for September's Laver Cup preparations on Monday, Federer was signing autographs for fans when one posed the question for the #1 ranking men's tennis player: are tennis balls green or yellow?

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"They're yellow, right?" he said, tentatively, before repeating himself with a little more confidence. "They're yellow!"

Sure, they might technically be more of a fluorescent yellow or maybe even arguably a chartreuse, but according to Federer, calling them yellow is perfectly adequate. His bold declaration got folks riled up, but whether or not you agree with him, the man does spend a lot of time around tennis balls so his opinion does hold some weight.

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There's only one way to solve this: someone ask Serena Williams.