Australian captain Michael Clarke and frontline pacemen Ryan Harris and Peter Siddle are to miss this week’s Sheffield Shield round ahead of the first Ashes Test.

England, meanwhile, is confident that injured pair Kevin Pietersen and Matt Prior will be fit in time for the Gabba Test.

With Clarke managing his well-documented back injury problem and Australia’s fast bowling ranks decimated by an injury crisis, the selectors are taking no chances with the key trio.

Instead of playing for their states, the skipper, Harris and Siddle will head to Cricket Australia’s new high performance centre in Brisbane to continue preparing for the opening Test at the Gabba starting on November 21.

Australian team coach Darren Lehmann said the decision to keep Clarke out of NSW’s Shield clash with Queensland in Brisbane was a “sensible” precaution.

“We’re very pleased with Michael’s preparation ahead of the first Test.

“The plan for his Ashes build-up was to play two Sheffield Shield matches, which he has done successfully.

“He has spent valuable time in the middle batting and fielding.

“Importantly his back has coped well in both matches, but we will continue to take a sensible and cautious approach to managing him.

Harris has been made unavailable for the Queensland team to play NSW while Siddle is ruled out of Victoria’s team to play Tasmania.

“On the fast bowling front, Ryan and Peter are both in great condition,” said Lehmann.

“As part of their management plan, they will continue their preparation under the guidance national coaching staff in Brisbane over the coming days.”

The Australian squad for the first Test will be announced on Tuesday.

England paceman James Anderson is optimistic about the fitness of Pietersen and Prior.

Star batsman Pietersen and wicketkeeper Prior will have respective knee and calf scans, with both suffering discomfort in the tour match against Australia A in Hobart.

Pietersen, who spent three months out with the same injury earlier this year, was to have a cortisone injection and did not fly with his teammates to Sydney on Sunday for their final warm-up match, staying behind for expert treatment in Melbourne.

However, by early afternoon (AEDT), he tweeted: “I AM FINE”, followed by “#relax”.

Anderson is also positive about the 33-year-old’s fitness ahead of this week’s four-day warm-up match against a NSW XI and also for the first Test from November 21 in Brisbane.

He told Sky Sports News: “I think Kevin’s gonna be fit for the game on Wednesday, which is good news.

“And Matt, I think it was a precaution he didn’t keep in the last game, and we’ve got our fingers crossed he’ll be fit for the first Test.”

Anderson believes it is sensible practice for England not to take any undue risks with their players.

“We’ve got a long five Tests ahead of us and we need Kevin for all of them if we can, so looking after them now is crucial.”

England spinner Graeme Swann was similarly positive about Pietersen and Prior.

“There were some very slight concerns last night but we woke up to very good news this morning.

“Kev’s had an injection and should be fit for Wednesday, and Matty Prior as well, he’ll bounce back and be ready in a couple of days.

“Luckily it’s happened to two of the fittest members of the squad.”

England coach Andy Flower still holds hope Pietersen can face the NSW Invitational XI and is confident he’s in little doubt for the Gabba unless the injection doesn’t take.

Prior is unlikely to play in Sydney but England are optimistic Prior will take the gloves in Brisbane.

Pietersen hasn’t made a substantial score in two months, dismissed for eight against Australia A and sitting out the tour opener against a WA Chairman’s XI.

With time running out, England’s ace is starved of time in the middle.

“I don’t think it’s going to be a huge issue. He’s had a couple of these injections before, and they’ve been successful,” Flower said.

“They’ve quietened the problem down, and it’s obviously an ongoing issue for him.

“But they have been successful, and we anticipate this one being successful and anticipate him playing a full part in the Ashes tour.

“… he’s got a little bit of time for the jab to work before we train on Tuesday.

“We anticipate him playing in the Sydney game.”