Phil Hughes is off to South Africa to join the Australian Test squad after Shaun Marsh was unable to overcome a calf injury he sustained in the fifth Carlton Mid ODI against England.

Cricket Australia (CA) confirmed the news on Thursday night with most of the squad already in South Africa.

"As Shaun Marsh’s calf injury has not improved as much as required over the past four days he has been withdrawn from the Test Squad for the Tour of South Africa," said Cricket Australia, in a statement.

"Phillip Hughes had been placed on standby and now comes into the Test Squad as a replacement for Shaun."

Hughes' flight details are yet to be confirmed but CA said Hughes will head there 'as soon as possible'.

The news should be received well by former Test players Dean Jones and Allan Border, who strongly suggested Hughes should have been selected in the squad when it was initially named.

Hughes' West End Redbacks high performance manager, Jamie Cox, said the left-handed batsman deserves his place on the tour.

"We are incredibly happy that Phil has been added to the squad; he has again been in fantastic form for the Redbacks and while we will miss his presence around the group, this is a great opportunity for him and just reward for his season,” said Cox.

“He was given feedback from selectors last year and has worked hard on some areas of his game. Phil has displayed resilience and determination, and we wish him the best in South Africa."

“This is a great opportunity for other players within the Redbacks squad to put their hand up and challenge for selection.”

Meanwhile, fears that injuries had weakened Australia’s first-choice pace bowling line-up before a ball was bowled in South Africa have lessened with the news that Jackson Bird is fit and about to join the touring party.

Bird was part of the 15-man squad named for the three-Test series that begins next month, but there was doubt he would make the trip after he injured his back while fielding during a recent KFC Big Bash League appearance for the Melbourne Stars.

The 27-year-old was pulled out of a Toyota Futures League fixture that he was expected to play earlier this week in order to receive ongoing treatment, and to undergo a couple of bowling sessions to gauge the extent of the injury and his capacity to recover.

He was put through his paces in the nets at Blundstone Arena in Hobart yesterday, under the watchful eyes of Australian coach Darren Lehmann and national selection panel member Rod Marsh.

As a result, he was given the all-clear by team medical officials today and will depart for South Africa tomorrow, along with Moises Henriques, to join the other members of the touring party who left Australia yesterday and are currently based in Potchefstroom where they will play a four-day warm-up game prior to the first Test in Centurion.

While he has not played a Test since the 2013 Ashes series in England when he succumbed to a back injury, Bird is regarded as an important of Australia’s fast-bowling plans should one of the incumbent quicks – Ryan Harris, Mitchell Johnson and Peter Siddle – be sidelined.

Tall and able to swing the ball both ways as well as generate movement off the pitch, Bird is similar in stature and style to Stuart Clark who made a memorable Test debut on South African soil in 2006 when he returned match figures of 9-89 at Cape Town.

On arrival in South Africa last night, spinner Nathan Lyon reaffirmed the underlying belief that the upcoming Test series will be dominated by pace bowlers given the respective strengths of both nations’ seam attacks.

"I think it's going to be pretty similar to Australia," Lyon said of the conditions that are expected to be tailor-made for fast bowlers.

"South Africa have a good pace attack as do we, so it’s going to be a pretty similar.

"Coming in off we what we just achieved in the Ashes series, full credit goes to our fast bowlers.

"They were fantastic the whole time so it will be a challenge for them to turn it around and back it up again and again.

"We've got to bowl in partnerships, and we do that the best in the world I believe."