Pat Cummins has been ruled out of the Australia A winter series against touring teams from India and South Africa.

The 23-year-old speedster had been expected to make his comeback from his latest bout of back stress fractures but his return has been pushed back.

Cummins last played for Australia in September 2015 in a one-day match against England, after which he was diagnosed with a lower lumbar bone stress fracture. He returned to bowling in February and had been hoping for selection to the senior side's winter tours of the Caribbean and Sri Lanka.

Initially starting with a run-up of just a few steps, Cummins has been steadily building up his bowling loads. However while the progress has pleased medical staff, the cautious approach will not see him at the required level of fitness or intensity to play competitive international cricket.

CA was keen to stress that Cummins had not picked up any new injury but they will not be swayed to rush him back into action.

His progress has impressed medical staff but still his timeframe for a return to competitive cricket has been adjusted from the August and September quadrangular Australia A series back to October's Matador BBQs One-Day Cup.

"Pat is going really well with his rehabilitation but is unlikely be ready to play at full match intensity during the Australia A tour," said CA's National Selector Rod Marsh.

"After discussions with Pat and the medical staff, we have decided to wait an extra month and look for him to return for New South Wales in the Matador Cup."

Cummins had only been planned to play in the white-ball component of the quadrangular series which features matches in Townsville and Mackay, and his participation had always hinged on the seal of approval from the medical experts, as Marsh flagged at the squad announcement in May.

The tearaway quick still boasts just the one Test to his name, and only eight first-class matches, as he continues to be carefully managed by CA amid the injuries with a strict 'white-ball only' policy.

Cummins told cricket.com.au in May he was confident of retaining the sort of 150kph pace that separated him from the vast majority of fast bowlers, but conceded that the mental challenges of rehab were becoming increasingly difficult with each injury.

"It's all about trying to work out a goal. I still get to come in (to Cricket NSW) and train every day and be around cricket," he said. "So it's still a pretty good job and lifestyle.

"It's each little win, each little step – being back in the gym for the first time, back running or having my first bowl – trying to get to that next goal.

"But certainly the more breaks I've had the harder it's gotten.

"It's great for me, James Pattinson, a couple of us young bowlers who have had a few injuries, that (Cricket Australia) really look after us. They give us good support and they don't rush us back. In terms of me wanting to rush back, they're more patient than I am, so I'm pretty lucky."

Cummins is the second big-name player to withdraw from the Australia A squad following news that Travis Head has been cleared to extend his contract with English county side Yorkshire.

Head has penned a deal with county side Yorkshire for the second half of the English county season, where he will replace New Zealand skipper Kane Williamson and again link up with Adelaide Strikers coach Jason Gillespie.

With obvious benefits in Head gaining valuable experience in England - with thoughts already turning to Australia’s next Ashes expedition in 2019 - CA released the 22-year-old from national duties in favour of an extended stint with the two-time reigning county champions.

"I have the great opportunity to play for Yorkshire and play four-day cricket there, it's something that I am really looking forward to," Head, told The Cricket Paper ahead of his arrival from the Caribbean tri-series.

"It will give me the opportunity to play in something that myself, everyone higher up and the coaches all say if a great opportunity - to go and play red-ball. I think it's a great thing they can see where I can get better and this is a good opportunity for me personally.

"It's definitely something I'm very conscious of, that I want to be very consistent and score big runs in four-day cricket, so hopefully I can start going that.

"It's being said from the top that I know what I have got to do to get better, and I was able to do that later on in the year which was a positive, so I am going in the right direction.

"I don't want to pencil myself in as (only) a white-ball player, I want to play Test cricket. So I think going and playing as many four-day games as possible, I think I can benefit from that and playing in different conditions."

Australia A squad: Ashton Agar, Cameron Bancroft, Scott Boland, Cameron Boyce, Travis Dean, Peter Handscomb, Sam Heazlett, Moises Henriques, Jake Lehmann, Chris Lynn, Joe Mennie, Kurtis Patterson, Joel Paris, Matt Renshaw, Kane Richardson, Alex Ross, Chadd Sayers, Marcus Stoinis, Mitchell Swepson, Chris Tremain, Dan Worrall, Sam Whiteman.

India A squad: Naman Ojha (capt), Faiz Fazal, Akhil Herwadkar, Shreyas Iyer, Karun Nair, Manish Pandey, Kedar Jadhav, Vijay Shankar, Axar Patel, Jayant Yadav, Varun Aaron, Dhawal Kulkarni, Jaydev Unadkat, Barinder Sran, Shahbaz Nadeem, Sanju Samson.

South Africa A four-day squad: Stephen Cook (c), Qaasim Adams, Temba Bavuma, Dean Elgar, Heino Kuhn, Sisanda Magala, Keshav Maharaj, Duanne Olivier, Wayne Parnell, Andile Phehlukwayo, Vernon Philander, Dane Piedt, Omphile Ramela, Stiaan van Zyl, Dane Vilas, Hardus Viljoen

South Africa A one-day squad: Wayne Parnell (c), Qaasim Adams, Marchant de Lange, Reeza Hendricks, Heino Kuhn, Eddie Leie, Sisanda Magala, Aaron Phangiso, Andile Phehlukwayo, Dwaine Pretorius, Rilee Rossouw, Malusi Siboto, Khaya Zondo, David Miller, Dane Vilas

Fixtures

Four-day matches

30 July – 2 August, Australia A v South Africa A, Allan Border Field, Brisbane 6 August – 9 August, Australia A v South Africa A, Tony Ireland Stadium, Townsville

One-day Series

13 August, South Africa A v NPS, Tony Ireland Stadium, Townsville 14 August, Australia A v India A, Tony Ireland Stadium, Townsville 16 August, Australia A v NPS, Tony Ireland Stadium, Townsville 17 August, South Africa A v India A, Tony Ireland Stadium, Townsville 20 August, Australia A v South Africa A, Tony Ireland Stadium, Townsville 21 August, India A v NPS, Tony Ireland Stadium, Townsville 24 August, NPS v Australia A, Harrup Park, Mackay 25 August, South Africa A v India A, Harrup Park, Mackay 27 August, NPS v India A, Harrup Park, Mackay 28 August, Australia A v South Africa A, Harrup Park, Mackay 30 August, Australia A v India A, Harrup Park, Mackay 31 August, South Africa A v NPS, Harrup Park, Mackay 3 September; Final 3 v 4, Harrup Park, Mackay 4 September, Final 1 v 2, Harrup Park, Mackay

Four-day matches

8-11 September, Australia A v India A, Allan Border Field, Brisbane 15-18 September, Australia A v India A, Allan Border Field, Brisbane