It seems like Johnny Walker’s highly anticipated move up to the heavyweight division has already hit a massive roadblock. According to MMA journalist Laerte Viana, Walker’s scheduled opponent, Ante Delija, has had to withdraw from their upcoming fight due to an injury.

The two were scheduled to fight at the historic UFC Fight Night 282 on August 1, headlined by Uros Medic and Daniel Rodriguez in a welterweight bout at Belgrade Arena in Belgrade. The event will be the promotion’s first-ever visit to Serbia. But now, with Delija out of the bout, UFC matchmakers are scrambling behind the scenes to find a replacement and keep the Brazilian star on the card.

The move to heavyweight is supposed to be a significant career reset for Johnny Walker. Standing 6-foot-6, the former top-15 light heavyweight has openly admitted that dropping down to 205 pounds was a nightmare.

The 34-year-old stated ahead of his recent split-decision loss to Dominick Reyes at UFC 327 that the brutal dieting had left him feeling completely depleted, dizzy, and missing the energy needed to train at full capacity.

“I’m thinking about it because the diet has been rough,” he told MMA Fighting. “If there’s an opportunity, if a heavyweight fight gets cancelled or anything, I’m in.

“I’ve been training with Francis Ngannou, sparring with him. Even while dieting, with about a 44-pound difference since I’m much lighter now, I’ve been able to train with him just fine. Even in wrestling, strength, and ground-and-pound. If I can do that while dieting, imagine without it?”

Coming off a 2-4 record in his last six fights, a fresh start at heavyweight is precisely what Johnny Walker needs—assuming the UFC can find someone ready to step in on short notice. In fact, with Ante Delija on the shelf, many fight fans online immediately came up with an incredible alternative idea for UFC Belgrade: Johnny’s younger brother, Valter Walker.

Are we nearing a Johnny Walker vs. Valter Walker clash?

The seeds of a potential family feud were planted earlier this year. After winning by submission at Karate Combat 59 in Miami, Valter Walker immediately used his post-fight interview to trash-talk his older brother, asking him to hurry up and make his move to heavyweight so they could settle things in the cage.

“I’m really upset because I called my brother to come here with me, and he didn’t come,” Valter said. “Look, Johnny isn’t here. I want to crush him! I have a kind of strange relationship with my brother now. I want to finish him off; I want to break his foot.

“I want to bring Johnny here and show him who the real Walker is… Everyone knows he has to ask his wife for permission. If his wife lets him, we’ll fight. I don’t care. It doesn’t matter where. Show me the money, and I’ll kill everyone and destroy everything. This is just the beginning. I’ll beat him here and in the UFC too. I’m just getting started.”

However, as fun as it would be to watch a real-life sibling civil war save UFC Belgrade, it isn’t on the cards just yet. Unfortunately for fight fans, Valter Walker is already booked for a heavyweight clash against Thomas Petersen at UFC Abu Dhabi on July 25, making a quick turnaround for August 1 nearly impossible.

However, once both brothers are done with their summer schedules, the UFC may have a historic opportunity on its hands. Sibling pairs such as the Diazes, Pettises, and Shevchenkos have left massive footprints on the Octagon, yet no two siblings have ever fought each other in UFC history.

If Johnny Walker can make it through his heavyweight debut in Serbia, a future battle against his own blood could be the most chaotic, must-see fight the promotion has to offer.