Mitchell Johnson has expressed his satisfaction at his current form for Australia in the Ashes against England and admits that a slight change in his technique has made a huge difference.

The bowler, who was a surprise inclusion in the squad prior to the beginning of the winter war, extended his series total to 17 wickets as the hosts comfortably won by 218 runs at the Adelaide Oval to take a 2-0 lead into their third match in Perth.

"When I sit back and look at it, I felt like my run-up rhythm was the best it's ever been," Johnson told reporters. "I've lengthened my run-up since coming back from my toe injury.

"That's made a big difference. I just feel like I'm getting better momentum through the crease and being able to hit those speeds without applying myself or forcing it. It feels pretty good."

The third Test gets underway at the WACA in Perth on Friday.