I know of just one Irish pub and no English ones (since Lord Jim's closed) in Rio, but I'm sure there are others. However, I agree that none will open at 4:30 a.m. (would have to get local staff to work, etc.).

If you are really serious about it, I'd contact the Aussie and Kiwi consulates in Rio but I doubt even their staff will see the game except at home, and that's only if it's available through the cable or satellite TV provider they subscribe to (I'm in Fortaleza and I'm pretty sure it won't be carried here, though I won't be getting up at 4:30 a.m. to confirm that). But if you can find a service that will carry it, you could start contacting hotels, etc. And those consulates may have ideas on where to look, even if they don't invite you to one of their homes to watch (I realize that's rude-- you wouldn't even insist on a hot breakfast, I'm sure-- but I was once a diplomat and know what they're like). I've found the array of chanels in hotels varying widely in quality and selection. Maybe you can find the game on the Internet?