But the goal-kicking centre has undergone intensive rehabilitation and hopes to rejoin the Brumbies for their crucial round 12 match against high-flying Western Force on
"My broken hand is progressing well," Mortlock said.
"I'm doing some training at Canberra at the moment, including a rehab run and a full week of speed work.
"I'll have further x-rays next week and if the bones have shown signs of mending then maybe I'll be able to ditch the sweet, purple-coloured cast that's been a part of me for the past two and a half weeks!
"I've had pretty intensive rehab and treatment over the past two weeks in Sydney, now I'm back in the act trying to put my game-face on and starting to training hard and preparing to play.
"I'm aiming to return for the match against the Western Force in a few weeks."
The broken hand is the latest setback in a horror season for Mortlock, after he was sidelined for three of the first five Super 14 matches with ongoing complications from two separate concussions he received against the Chiefs and the Queensland Reds.
But thanks to the leadership of veterans George Gregan and Stephen Larkham, and the outstanding form of utility back Julian Huxley, the Brumbies have been able to deal with Mortlock's absence.
The Canberra-based team have just completed a solid tour of South Africa with wins over the previously unbeaten Sharks in Durban and the Lions in Johannesburg, and have soared to fifth spot with just five rounds to go until the Super 14 semi-finals.
"I think everyone's aware that we are coming into the business end of the season and we've gained a lot of confidence from the last few weeks on the road," said Mortlock.
"You want to be going into this part of the season in good form and I think so far it looks as though we're starting to find our game a bit more, compared to the start of the season."