The fifth seed faces his good friend on Friday after stunning world number one Rafael Nadal in the last eight, with a crack at either seven-time champion Novak Djokovic or six-time winner Roger Federer at stake.
Thiem and Zverev have played each other eight times, with the Austrian holding a 6-2 advantage, including their last two encounters. They have never been forced into a five-setter.
“We have no secrets from each other. I mean, we played so many times, also on very special occasions already, at the ATP Finals, semis, French Open quarters,” said the 26-year-old.
“It’s a nice rivalry we have. It’s great that we add an Australian Open semi-final to this one. Going to be a close match again.”
“Same if two top-10 players play each other (in the) semis of a Slam. The deciding moments are very small, small margins. I’m looking forward to it,” he added.
Thiem is better known as a clay-court specialist and has experience of the big time, making the French Open final over the past two years, beaten each time by Nadal.
But this is the furthest he has got on hard courts at the Majors and knows he is on the cusp of a crack at shattering the stranglehold Djokovic and Federer have had on the tournament, sharing 12 of the last 14 titles.
“One of us is going to be in the finals. But it’s still a very long way to go,” he said.
Seventh seed Zverev has long been tipped for great things, but until now the 22-year-old has failed to deliver at the Majors.
He is into his first Grand Slam semi-final after taking a more relaxed approach, admitting that in the past he was trying too hard to make his mark.
– Bushfire pledge –
“In a way, I was maybe paying attention to it too much, to the Grand Slams. You know what I mean?” he said.
“I was just playing better tennis at the other tournaments. At Madrid, Rome, other Masters, the World Tour Finals. The Grand Slams maybe meant too much for me.
“This year I actually came into the Australian Open with absolutely no expectations.”
Taking the pressure off has worked wonders, with Zverev battling past former champion Stan Wawrinka and dangerous Russian Andrey Rublev en route to his clash with Thiem.
Regardless of what happens on Rod Laver Arena on Friday, he is content with his tennis, and his life.
“Do you have to prove a point to anybody in this world? Maybe to your parents, out of respect or something like that,” he said.
“But anybody else, this is your life. You do with it what you feel is right. All I’m going to say, I’m always going to try my best.
“I am always going to do everything I can to win tennis matches, to at least do the best thing I can on the tennis court when I’m playing in front of people, just to have respect in front of the crowd.”
Zverev has already gone a long way to winning over Australian fans, donating $10,000 for each match he has won to the country’s bushfire relief fund.
If he claims a maiden Grand Slam in Melbourne on Sunday, he has vowed to also hand over his Aus$4.12 million ($2.78 million) winner’s cheque to the same cause.