At UFC 196, Diaz was moving away from a lot of the punches, reducing the impact. On Saturday night, though, Diaz was coming forward, absorbing the full power of McGregor's left hands. And eating every one of them.
"You can't get a heavier shot than that," Kavanagh said Monday on The MMA Hour with Ariel Helwani. "And what does Nate do? Puts his hands out and walks forward. I'm not gonna lie, I was slightly terrified."
McGregor did end up winning the hard-fought, bloody contest by majority decision (48-47, 47-47, 48-47). But Diaz was in it until the end, winning the fifth round on the judges' scorecards and taking a dominant third frame. Diaz, of course, won the first fight via second-round submission.
In past fights, opponents have been melted down and put out by McGregor punches. Not Diaz. He was knocked down once in the first and twice in the second. But was never really in any danger of being finished. Somehow.
Kavanagh believes Diaz is McGregor's staunchest test and will continue to be that moving forward.
"For me, I was looking at him just taking these heavy shots and walking forward, smiling," Kavanagh said. "In my head, I'm going, I'm glad I'm on the outside here. This is insane that Conor has hit him with everything. It's an incredible ability Nate has. That's why I think it's the toughest fight."
One particular moment stood out to Kavanagh. It was the fourth round, the one in which McGregor rallied and all but sealed the fight. McGregor went for a spinning back kick to Diaz's body and Kavanagh corrected him.
Kavanagh shouted to McGregor to stick to the game plan. Diaz replied back, to the McGregor corner, "F*ck you and your game plan."
"It was a crazy moment," Kavanagh said. "I'm having a conversation with him. His eye is all over the place. That was deep in round four."
The build up for this fight was intense and the actual in-cage action was even better. McGregor seemed angry all week. When Diaz and his team stormed out of the pre-fight press conference with an ugly bottle-throwing scene ensuing, McGregor could be seen on UFC Embedded absolutely furious.
At open workouts, McGregor ripped Diaz and his team and cursed them out. He said if anyone was with them "f*ck you, too," and flipped the microphone in the air.
Kavanagh planned on sitting down with him and giving a "long, boring speech" about staying disciplined and being focused. But after the weigh-ins, McGregor came backstage and looked his coach dead in the eye like a "serial killer," Kavanagh said.
"The illusion of insanity is over," Kavanagh said McGregor told him. "Now it's time for the game plan."
The game plan worked and led to a victory. But that doesn't mean Kavanagh came away any less impressed with the borderline indefatigable and bulletproof Diaz.
"I think this is possibly the toughest fight that Conor is ever gonna have," Kavanagh said. "Who else can walk through shots like Nate can?"