Former Manchester United captain Roy Keane tallied up a lot of fierce rivalries over the course of his playing days, but there's only one club that still gets on his nerves post-retirement.
And it's not who you'd expect.
Speaking in a Sky Sports panel alongside Thierry Henry and Kenny Dalglish to celebrate 25 years of the Premier League, the Irishman opened up about his aversion to Chelsea.
"The owner, clearly, was going to throw money at it," the Irishman said.
For those who don't remember, Russian oligarch Roman Abramovich purchased the club in 2003 and bankrolled his team to success, signing big names and hiring Jose Mourinho in 2004.
"Listen, they've thrown hundreds of millions at it and will probably continue to do so and that's what makes them a decent team... I remember growing up watching Liverpool in the 80s. Brilliant. We'd respect for Arsenal. I've always found it hard to kind of like Chelsea even though. I'm still reluctant - the way they've done it. Whatever way they've done it, I find it kind of hard to praise them too much but that's just a personal thing."
So there you have it, Roy Keane harbours grudges – just not the ones you'd expect.
Watch the full interview below: