Warburton and co won by just two points in round one, with Horwill's troops edging home by the smallest margin possible with a 16-15 triumph in round two.
The stage is now all set for a thrilling finale in New South Wales next Saturday and Horwill is convinced things will follow a similar pattern in Sydney.
"It will be close again next week - I'm predicting there will be one or two points in it. Both teams are pretty evenly matched and we're feeling each other out," said Horwill, after a late converted try from Adam Ashley-Cooper won it for the Wallabies.
"They've both been intense games so far and they've come down to crucial moments. But that's what Test-match footy is.
"All bets are off this week, it's all square. It's one game to win it, it's like a cup final. We've got a bit more footage of them and they've got a bit more of us so the game of chess will continue now. I love every time I get to play in this jersey and to do so in a game of that magnitude on Saturday will be huge.
"I'm sure they will bounce back like any quality team. They've got guys who have played a lot of Test match rugby, they know what it's about. A lot of them have played big games at club level and at Test level. I'm expecting it to be the toughest game yet of the tour."
Horwill praised his side's mental strength and will to win after they overcame a 15-9 deficit knowing that time was running out to take the series to a final weekend.
The 28-year-old second row insists he never doubted his team's desire or their ability to dig deep, even when they were on the edge of extinction as far as the current series was concerned.
"The guys always keep fronting up, no matter what's happening and what the score's doing. As a captain, you couldn't ask any more of a group," added Horwill.
"The attitude and the character of the group is something you can't coach. You can't sit on a training field and say 'this is what you've got to do to show character and show attitude: it's something that comes from within and it's very pleasing to see how much it means.
"We were disappointed it got to that stage of letting them have a shot to win it. We should have shown a bit more composure and ended a bit more calmly, rather than letting them get that penalty.
"There was an equal share of relief and jubilation at the end of the game. We worked hard for that. Although not everything went right, we found a way to win. That's what teams need - to find a way to win."