Left-arm fast bowler Johnson took 37 wickets at 14 apiece as Australia thrashed England 5-0 on home soil to regain the Ashes in 2013/14.
Johnson, however, was mocked by England fans while going wicketless during the first innings of Australia's 169-run defeat in Cardiff in the opening match of the current Ashes campaign.
Read: England's Bell eager for Ashes turnaround
It was though a very different story in the second Test at Lord's, where Johnson had match figures of six for 80 during Australia's crushing 405-run win that levelled the five-match series at 1-1.
England captain Alastair Cook may be in better form than Australia counterpart Michael Clarke but that counted for little as the hosts, with Johnson taking three cheap wickets, slumped to a humiliating 103 all out in their second innings.
But a defiant Root said of Johnson: "It's wrong to single one man out. You look at Cardiff and he only got two expensive wickets so it's about putting him under pressure."
England have responded to their drubbing at Lord's by dropping Gary Ballance and promoting the experienced Ian Bell -- himself struggling for runs -- to Ballance's positon of number three, with Jonny Bairstow coming into the side at the expense of his Yorkshire colleague.
Australia left-arm fast bowler Mitchell Starc was not concerned by England's attempts to stabilise a top order that has been 43 for three or worse seven times in their past 13 Test innings and promised there would be no let-up from the tourists' pace attack.
Read: Mitchell Starc pitches into England
"I am sure we will be following suit from what Mitch (Johnson) dished up at the end at Lord's," said Starc.
"It is great to see a few of the guys jumping about, and we got a few wickets that way. We have got extra pace in our side."
This year has seen England bounce back from defeats by the West Indies and New Zealand with a win in their very next Test.
"Throughout this summer we've always come back from heavy defeats well," said Root.
"There's so much confidence in the camp and we'll be looking to put them back on the back foot on Wednesday."
The second Test defeat prompted England's Australian coach Trevor Bayliss to call for a livelier surface than the one on which England great James Anderson went wicketless at Lord's.
But Starc was unconcerned by the state of the Edgbaston pitch.
"It doesn't matter what they dish up, we've got all bases covered," he said.
Bell has scored just one fifty in 12 Test innings since he made a hundred against the West Indies in Antigua three months ago.
In welcoming his promotion to number three, Bell -- looking to become the first Warwickshire batsman to score a Test hundred at Edgbaston -- said Monday: "I know I haven't performed to the best of my ability in the last two months.
"It's a good opportunity to take some responsibility and score some runs."
Bairstow's recall for his first Test since he featured at Sydney last year is set to be England's lone personnel change after fast bowler Mark Wood, who has a history of ankle trouble, came through Monday's net session.
Bairstow is averaging over a hundred in the County Championship this season, having scored five centuries, but how well that has prepared him to face Australia's quicks remains to be seen.
Australia, meanwhile, are set to field an unchanged side.
Opener Chris Rogers, who made a Test-best 173 in the first innings, is set to be given the all-clear after a balance problem in the inner ear forced him off the field on the fourth and final day at Lord's.
Wicket-keeper Peter Nevill is also likely to retain is place after impressing on debut last time out even though Brad Haddin is available again after withdrawing for "family reasons" ahead of the second Test.
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