Johnson terrorised the England batsmen in Brisbane and Adelaide, taking his side to the brink of reclaiming the Ashes after three consecutive series defeats. (Agencies)
And the left-arm quick, who has taken 17 wickets with his 150 kilometres-an-hour (93 miles-an-hour) deliveries, has been tipped to bowl even faster on his home ground, the WACA, in the match starting on Friday.
Despite the England batsmen being bruised and battered, Flower rejected claims they were afraid of Johnson.
"I wouldn't say scared. One thing I would say about playing fast bowling is that our batsmen have to display the combination of skill and determination to bat long periods against it," he said.
"Because if we do expose our lower order, they will struggle against that sort of pace. So the responsibility lies with the batsmen in that regard."
Johnson Wednesday said he was excited by the chance to fire in some bouncers at England on his home turf, but he doesn't plan to focus too much on the speed gun.
"I'm not worried about bowling 155, 160 clicks," he said."I don't think that's important to me. When my rhythm is on, the ball comes out the way it does and it's at good pace."
England have a sorry record in Perth, where their only win in 12 attempts came in 1978. But they must find a way to halt the Australian juggernaut since victory would give the hosts an unbeatable 3-0 lead in the five-Test series.
Johnson terrorised the England batsmen in Brisbane and Adelaide, taking his side to the brink of reclaiming the Ashes after three consecutive series defeats.