That came three years ago, when the Australian, 27, suffered a serious shoulder injury that he feared might prematurely end his career.
“I worked in the City for a little bit at one of my mate’s companies,” said Millman ahead of today’s match. “I was dressed up in a suit each day going in.
“I always wanted to get back into tennis. Great credit to the guys out at the National Academy in Brisbane. They really pushed me along. Friends and family supported me through that time.
“I think I really have an appreciation of these moments right now, because there was a big time there where I wasn’t too confident.
“You dream of playing on the biggest courts against the biggest players. I feel as if I deserve to be there. I have played two good matches to get through.
“I have never been one to necessarily go out with an intimidated mindset before I play. I think that that’s kind of being disrespectful to the game. So we are going to start at 0-0. I’m going to give it everything.”
Millman had been on the verge of the top 100 when injury struck. When he returned almost a year later, his ranking dropped outside 1,000 and he found himself back on the Futures Tour, the lowest level of professional tennis.
The genial man from Brisbane was not discouraged, though, and by the end of 2014 was back inside 200 before breaking the 100 barrier a year ago.
“I got lucky with a few results early on, which really helps,” he said. “I really feel sorry for guys who obviously work hard to get back from a big injury and those first few results don’t go their way.
“At the start of 2015, I played Federer in Brisbane. It took a very long time to get myself right over 12, 13, 14 months, but I was rewarded pretty quickly by being able to play probably one of my greatest idols.
“So, when there’s bad times, you never know when a good thing is around the corner.”
Millman is now ranked 67 and, although he has only played Murray once before, he is no stranger to taking on and beating British players.
His only defeats against Britons have come against Murray and Dan Evans and he can boast 10 victories.
Despite that, Millman is popular with a lot of the British players and spends a lot of time with his fellow Liverpool fan Beverley’s Kyle Edmund.
His one meeting with Murray came in his home-town tournament prior to his injury in 2013, and he took a set off the world No 2, who remembers being very impressed.
“I didn’t know him before we played in Brisbane,” said the Scot. “I knew it was his home town. He played extremely well that day. He was ranked about 200 at the time.
“I came off the court and I said to Dani Vallverdu, who I was working with, ‘He’s top 50 for sure if he keeps going’. I don’t know what his ranking is now, but he’s pretty close, I think, to that.
“He moves well. He has a great attitude. He’s played a few good matches there in Brisbane. But, obviously, it’s a different surface, different place. The match-up will be a bit different on a grass court.”
Another difference will be the attitude of the crowd.
“He’ll probably have a bit more support,” said Millman, who knocked out 26th seed Benoit Paire to reach the third round at Wimbledon for the first time.
“I don’t think anyone was going for him back in Brizzie. It’s a bit of a reversal of roles. Obviously, it’s a little bit different now at Wimbledon, but it’s what you dream of.
“I love playing in Brisbane. It’s an unbelievable tournament for me. I train there. You’re just familiar with the surroundings so much more.
“I’m sure it’s the same with Andy here. He’s played it that many times. I have never been inside Centre Court or Court One. Maybe Wimbledon will put us on Court 16, because I played on that one.”
Murray will hope for another trouble-free outing, having defeated Liam Broady and Lu Yen-hsun in straight sets, losing just 15 games.