Turns out Rob Gronkowski won’t be the only superstar athlete retiring this week.

UFC superstar Conor McGregor stunned the sports world early Tuesday when he took to Twitter to announce his decision to walk away from mixed martial arts.

It’s worth noting this isn’t the first time McGregor has called it a career. That said, his previous retirement tweet was much less formal and direct than Tuesday’s.

UFC president Dana White is also selling the most recent announcement, telling ESPN’s Brett Okamoto he’s “so happy for (McGregor) and I look forward to seeing him be as successful outside of the octagon as he was in it.”

Throwing in the towel didn’t appear to be in McGregor’s plans as recently as last week. The Notorious, as captured by TMZ, vocalized his intention to fight Nate Diaz for the third time, saying “… I owe him the trilogy now and the trilogy will happen.”

If McGregor truly is finished in the octagon, he’ll have gone out on a bit of a sour note. The 30-year-old last October suffered a fourth-round submission loss to Khabib Nurmagomedov, who seemed to be a prime candidate for a future McGregor match as well. Still, the Irishman’s 21-4 professional MMA record speaks for itself.

A future comeback also seems entirely possible Just look at one of McGregor’s past opponents, Floyd Mayweather Jr., for example. The legendary boxer was comfortably settled into retirement before being present the megabout with McGregor. If McGregor down the road is presented a lucrative in-ring opportunity, it might just be too good for him to pass up.

Then again, it’s safe to say McGregor will have no shortage of business avenues moving forward. The decorated fighter is one of the more vibrant and charismatic athletes in recent memory, which likely will allow him to make a killing in the entertainment industry, much like Gronkowski.

All told, you really can’t rule anything out when it comes to McGregor’s future.

Thumbnail photo via Stephen R. Sylvanie/USA TODAY Sports Images