The WBA (Super), IBF, WBO, and IBO heavyweight champion posted videos and pictures on Instagram of himself watching Chelsea's last-16 clash with Lille.
The boxer even has some professional football experience himself as a substitute for the Ukrainian second-division team FC Polissya Zhytomyr in a 2-1 win over NK Veres Rivne earlier this month.
He put in a solid showing, but this time he was content to be in the crowd.
Although the Ukrainian is not a Chelsea fan, instead he is a Man City supporter and once celebrated with the team after a Manchester derby win back in 2018.
Usyk is edging closer to his rematch with Anthony Joshua after outclassing the Brit at the Tottenham Hotspur Stadium in September.
AJ was offered £15million to break his rematch clause with Usyk and it is understood he was also guaranteed a shot at the winner of Fury vs Usyk with all four belts on the line.
But Joshua turned down the cash and is now set to face off against Usyk again on a make-or-break night.
"There's a lot of places very interested in holding that fight, it's the biggest heavyweight fight so far this year - the biggest heavyweight fight available right now," Eddie Hearn said.
"There are a number of countries in the Middle East that I was there visiting last week, I spoke to [Tottenham chairman] Daniel Levy again at Spurs, who would love to have the rematch back there.
"I would love to see the fight take place in the UK, but obviously Usyk will have some say in that as well, and they're gonna wanna go wherever the most money can be generated.
"There's no deal to get done; the deal's done, the contract's signed. It's just a case of agreeing the location and date, which should be imminent."