Designated all-rounder ... Mitchell Johnson will bat at No.7 for Australia against Sri Lanka in the SCG Test.

Designated all-rounder ... Mitchell Johnson will bat at No.7 for Australia against Sri Lanka in the SCG Test. Photo: Getty Images

Fast bowler Mitchell Johnson will bat at No.7 for Australia against Sri Lanka at the Sydney Cricket Ground after captain Michael Clarke announced Victorian all-rounder Glenn Maxwell as 12th man for the third Test.

With the SCG pitch having an unexpected green tinge, the Australians have opted for Jackson Bird's seam bowling ahead of Maxwell's off spinners.

Since returning to the Australian Test team this summer, Johnson has taken 12 wickets at 20.25 and scored 102 runs at 51 

With Shane Watson unavailable due to a calf muscle injury, Clarke will bat at No.4.

Matt Wade.

Matt Wade ... elevated in the batting order. Photo: Getty Images

Retiring veteran Mike Hussey moves up a spot to No.5, wicketkeeper Matthew Wade will bat at No.6 followed by Johnson, who smashed an impressive 92 not out during his man of the match performance in Melbourne last week.

NSW left-armer Mitchell Starc, who was controversially rotated out of the team for the second Test, will play on his home ground.

Clarke said Johnson’s form with the bat combined with the state of the pitch had dictated selection.

‘‘A fair bit of grass on the wicket, the boys bowled really well in the last Test match,’’ Clarke said.

‘‘And bringing Mitchell Starc back into the team obviously helps our attack, especially with the form he’s in.

‘‘Mitchell Johnson’s batting, he’s batting as well as an all-rounder now anyway.

‘‘I’m confident we’ve got enough batting still with Matthew Wade at six and Mitchell Johnson at seven and we’ve got extra bowling which is a real positive for us.’’

Johnson, 31, showed his potential as an all-rounder during Australia's three-Test tour of South Africa in 2009 when he topped the batting averages for the tourists with 255 runs at 85 including his only Test century, 123 not out in Cape Town, and an unbeaten 96 in Johannesburg. The left-arm quick also took 16 wickets at 25 as was named man of the series in Australia's 2-1 series win.

Since returning to the Australian Test team this summer, Johnson has taken 12 wickets at 20.25 and scored 102 runs at 51.

Johnson has shown signs that he’s tightened up his game without compromising on his vicious pace.

If he can stand up as a consistent strike weapon for his country in India and in the Ashes, he will be well on his way to building a lasting Test legacy.

‘‘I certainly didn’t think it would be the last of Mitch. I’ve always known how much talent he’s had. He’s one of the greatest athletes I’ve seen play cricket,’’ said Clarke.

‘‘I think Mitch’s time away from the game freshened his body and also freshened his mind.

‘‘He’s as hungry as he’s ever been. With the right attitude, you go a long way to playing your best cricket.

‘‘We left him out in Hobart and he had the right attitude. He made it clear he wanted to be back full-time.’’

Queensland batsman Usman Khawaja remains on standby for Clarke, but the skipper is expected to overcome a hamstring problem and play.

‘‘I think my hamstring’s better than it was in Melbourne. If I didn’t think I could perform at my best I wouldn’t take the field,’’ Clarke said.

‘‘It certainly won’t be because of my hamstring that I don’t make a big score.’’

Maxwell, who combines his off-spin with aggressive batting, was expected to get a run in Sydney to give him some experience before his likely selection for the tour of India.

However, Clarke said he was not concerned about upcoming tours to India and England this week, with his sole focus on completing a 3-0 clean sweep over the Sri Lankans.

Australia: Michael Clarke (capt), David Warner, Ed Cowan, Phil Hughes, Mike Hussey, Matt Wade, Mitchell Johnson, Peter Siddle, Mitchell Starc, Jackson Bird, Nathan Lyon, Glenn Maxwell (12th man)

Fairfax Media and AAP