The 30-year-old British No 1 and three-time major victor has slipped to 16th in the world rankings, having been sidelined by hip problems since Wimbledon. "Everytime I wake up from sleeping or napping i hope that it's better and it's quite demoralising when you get on the court it's not at the level you need it to be to compete at this level", he said.
'I want to enjoy playing again, ' Murray said at a press conference. I've really missed it the last six months or so.
His withdrawal was confirmed hours after Garbine Muguruza, the Wimbledon champion and women's top seed, retired from her opening match because of leg cramps. "The rest of my body feels really good".
After his 6-7 (5-7) 7-6 (7-4) 6-4 win, the Brit will take on South Korea's Hyeon Chung.
I'm very disappointed to be withdrawing from the Brisbane International.
The forthcoming clash between the players will be the first since the first round of the 2012 Australian Open, when Murray had to come from a set down to kick-start a campaign that eventually saw him reach the semi-finals.
The Scot had been due to face Ryan Harrison in the last-16 at the Australian Open warm-up event but the American will now advance to the quarter-finals after the 30-year-old's exit.
Players in general are taking more and more time off to recover for the upcoming season. "Surgery is also an option but the chances of a successful outcome are not as high as I would like which has made this my secondary option and my hope has been to avoid that".
And while his ultimate target is January's Australian Open where he is a five-time runner-up, Murray has suggested the days where he competes for major honours could be behind.