Commentators, Cahill to be specific, correct that RBA just getting better depth, more consistently this set. And Djokovic hasn't been able to deal with it well. He's dealt with it ok though. And he's irritated. The crowd noise pulling him out of focus. And he's missing more. And he's still only down a break that RBA likely only got because Djokovic's string broke. So still not too much to worry about for him. Though I'd love to end up being wrong about that. Hopefully RBA can keep this up and first get this set. But also push Djokovic after this set as well.
Either way, you can see how RBA has beaten Novak in best of three twice this year. He just keeps plugging away. Gets better as the match goes on. Doesn't mind losing a set. Knows what he's up against and trusts himself enough to trade blows with Djokovic. And. This is how confidence works. You beat Djokovic twice in a year and then get a favorable draw at a slam and suddenly you're making your first slam semi. After making your first slam quarter at the AO (l. Tsitsipas in 4 sets).