Jose Aldo is preparing to fight Frankie Edgar at UFC 200 on July 9, but he has unfinished business with Conor McGregor. The most dominant featherweight in UFC history has moved on from his stunning loss to the brash Irishman, but he’ll have to beat McGregor in order to get his belt back.

Aldo and McGregor have fought just once, but their rivalry began nearly a year and a half ago, and it could continue through the end of 2016. Seconds after McGregor beat Dennis Siver on Jan. 18 of 2015, he ran out of the octagon to confront Aldo, who was sitting cageside. That set up the title fight between the two that was supposed to happen at UFC 189 in July, but was delayed until UFC 194 in December because Aldo suffered an injury.

McGregor needed just 13 seconds and one punch to win the belt that Aldo had held for over five years. Aldo wasn’t granted an immediate rematch as McGregor went on to face Nate Diaz in a welterweight fight at UFC 196, and the interim title fight at UFC 200 will determine McGregor’s next challenger.

Aldo plans on knocking out Edgar, whom he beat three years ago, and he’s certain that another fight with McGregor would produce a different result.

“That was a rare occurrence; it’s like a Comet Halley passing – it only happens once every 100 years,” Aldo said at a UFC 200 press conference on Wednesday, referring to his loss in December.

Prior to UFC 194, Aldo was one of the most dominant fighters UFC had ever seen. He was the only person to hold the featherweight title, and he hadn’t lost in over a decade. Now, McGregor has what Aldo believes is rightfully his.

The rivalry between Aldo and McGregor seems to be about more than just the title. Aldo has criticized the way McGregor handles himself away from the cage. McGregor was pulled off the UFC 200 card by UFC president Dana White when he refused to travel to Las Vegas and take part in the promotional tour for what’s expected to be the biggest pay-per-view in UFC history.

McGregor suffered his first ever loss in UFC when he was submitted by Diaz in March, and he had been preparing for their rematch at UFC 200. But he didn’t want to fly to Las Vegas from Iceland as he looks to correct the mistakes that cost him in the first fight.

"That proves how weak he is," Aldo told ESPN. "I don't see him as an athlete, I don't respect him. In my opinion, he's weaker than everything he always said."

Much of the conversation surrounding UFC 200 has been about McGregor, even though he’s been off the card for over a week. He announced his retirement on Twitter before he was taken off the card, but that didn’t last for more than a day. On Monday, McGregor announced on Twitter that he was added back onto the PPV, even though that wasn’t the case.

“I think for a while he thought he was bigger than UFC, and that’s not true because no one is bigger than UFC," Aldo told International Business Times on Tuesday. “All of us will pass, but UFC goes on. So I think that he may have thought he was bigger than he is.”

It’s uncertain when McGregor will put his featherweight belt on the line, though White has suggested it could be at UFC 202. There’s been speculation that the Aldo-Edgar winner could face McGregor at UFC 205 in November, though White has indicated he wants McGregor to defend his title before then.

There’s always the chance that the July 9 interim featherweight title fight becomes the actual championship fight. McGregor has already passed up two opportunities to defend his belt, and Edgar isn’t sure that McGregor will ever come back down to fight in the 145-pound division.

But Aldo remains unconcerned with McGregor's headlines.

“He can do whatever or say whatever he wants,” Aldo said. “I need to concentrate on doing what I do best, and training hard and fighting hard, which is what I do.”