Ryan Harris has been officially ruled out of Australia's upcoming Test series against Pakistan and it remains unclear when the veteran paceman will be available for selection again.

Harris underwent major knee surgery in March after bravely steering Australia to a series-clinching victory in the third Test against South Africa in Cape Town.

The world's No.2 ranked Test bowler had initially been hopeful of returning for the two-Test series against Pakistan in the United Arab Emirates in October, but Australian team physiotherapist Alex Kountouris confirmed on Tuesday that Harris would not be picked.

"We're certainly not looking to him to be right for the UAE at the moment," Kountouris said.

"He's going to start running in the next couple of weeks and we'll see how his knee responds to that and hopefully it'll respond the way we expect.

"If he copes with that, we'll transition him into bowling.

"We're looking for him to be able to play somewhere before Christmas.

"Hopefully it'll be the India Test matches and he'll play some Sheffield Shield matches before that, but until he starts running and then bowling it's very hard to predict what's going to happen."

Although the fast bowler remained hopeful, privately he had accepted for some time that he would not be fit in time for the UAE and had adjusted his recovery programme accordingly.

The 34-year-old's performance against the Proteas at Newlands in March was one of the most courageous from a fast bowler in recent memory.

In desperate need of knee surgery and also battling a hip flexor injury, Harris produced one final effort to take the last two wickets of the match and secure victory with just 27 balls remaining.

Harris went under the knife just days later and forecast a long and difficult recovery process ahead.

"I've said all along that long breaks aren't good for me," he said at the time.

"This one is an enforced one so it's going to take a lot of hard work to get up and going.

"I just want to do whatever I can now to keep playing in this team and enjoying the success that we've been working so hard to get to.

"This is nowhere near my career over."

Cricket.com.au has been exclusively following Harris's recovery from the operation on his right knee. Unprecedented access saw our cameras follow Harris as he had a crucial MRI 12 weeks after surgery.

After battling injury for most of his career, Harris finally found some continuity last season and played a crucial role in Australia's victories over England and South Africa.

He played 12 consecutive Tests between last July and March this year, improving his already impressive Test record to 103 wickets at an average of 22.56 from 24 matches.

While out of action, Harris has taken on coaching duties, working with the Australia A bowlers ahead of and during the current tour.

The Brisbane-based fast bowler has been working intensively with Cricket Australia's sports science and sports medicine staff at the National Cricket Centre with his progress monitored daily.

If fit, Harris will be a crucial weapon in Australia's armoury ahead of a busy 12 months for Michael Clarke's side.

Following the Tests against Pakistan, Australia face a home series against India this summer before Test tours of West Indies and England next year.

Harris has also expressed a desire to play a role in the ICC World Cup in Australia and New Zealand next year, despite not having played a one-day international since February 2012.

Harris returned to cricket action in June, when his healing knee allowed him to pick up a bat and play front-foot shots in the nets with the use of a ProBatter machine.