Andy Murray narrowly avoided the wrath of coach Ivan Lendl after labouring to a 6-1, 5-7, 6-3 victory over Australian qualifier John Millman in his opening match at the Brisbane International.

The US Open champion ran hot but mostly cold against the 199th-ranked player in a match of wildly-fluctuating tennis that lasted two hours and four minutes at the Pat Rafter Arena.

The 2012 Olympic gold medallist revealed that former world No.1 Lendl, who was due to arrive in Brisbane on Friday, had not even considered the possibility of the Scot losing to Millman.

Before the second-round match, Lendl had sent a text message to the 25-year-old's hitting partner Danny Vallverdu asking what time Murray's quarter-final with Uzbekistan's Denis Istomin would be on Friday.

"December 22nd was the last day we trained in Miami before I went home," said the Scot.

"He messaged Danny and said 'Can you send me the score and what time he's playing tomorrow before the match?'. He hadn't heard of John before.

"He was obviously expecting me to come through, but it was very nearly a different story. The depth of the game now is so, so strong. None of the matches are easy.

"It was a bit different back in Ivan's day where they could kind of cruise a little bit for the first couple of rounds."

Murray was horribly out of sorts in a tight second set, clutching at his back, thigh and shoulder. His class shone through, but it was not one of his finest efforts.

"I had spotted John's name before, but I hadn't seen him play," said the Scot, who will look to build on his US Open Grand Slam win at the upcoming Australian Open later this month.

"I think it's important when you don't know how someone plays to find out about their character a little bit.

"He's very consistent, he can play quite a long way behind the baseline and doesn't take too many risks.

"And then, you know, he was going for absolute bombs and making them."