Clarke has been struggling physically with a hamstring injury and emotionally in the aftermath of friend and former team mate Phillip Hughes's death, which caused the opening test to be postponed and moved from Brisbane.
"It’s a huge boost to have him back in and playing for us," Johnson told reporters at Adelaide Oval on Monday.
"He has been working really hard out there. I’ve got no worries (about him) at all.
“He’s said he’s 100 percent fit and you go by that. He’s always been a hard worker. You’ve got to put trust in him."
Clarke had been in a race to be fit after suffering his third hamstring strain in three months during the one-day series against South Africa.
His rehabilitation was disrupted by the tragic death of Hughes as he devoted virtually all his time to be at the batsman's bedside during his two-day fight for life in a Sydney hospital.
Clarke also stayed in Hughes's hometown of Macksville, New South Wales, for a day after the funeral to be with his Hughes's family for the cremation.
Prior to Hughes's death, the struggling skipper was at loggerheads with team selectors over how to prove his fitness for the first test of the four-match series.
After the tragedy, Clarke drew huge public support as he swallowed his grief to take a lead role in supporting Hughes's family and stunned team mates.
"I think with his captaincy, he’s shown how strong he’s been over the last couple of weeks with the tragedy that we’ve had," Johnson said.
“It has been an emotional roller-coaster and how strong he has been as a person to stand up and do what he’s done.
“I’ve definitely seen a different side to him.
“He has just grown as a captain and as a person."
Johnson said uncapped paceman Josh Hazlewood and reserve batsman Shaun Marsh would not play, leaving Ryan Harris and Peter Siddle to join with the ICC Cricketer of the Year in the pace attack.
Team: Michael Clarke, Brad Haddin, Ryan Harris, Mitchell Johnson, Nathan Lyon, Mitchell Marsh, Chris Rogers, Peter Siddle, Steve Smith, David Warner, Shane Watson.
(Reporting by Ian Ransom, editing by Peter Rutherford)
Share
