Calcutta: The aspect of retirement seems to be floating in the mind of Mitchell Johnson although he says he's trying to enjoy each and every game that he plays.

Speaking to the media on Wednesday in Perth, the left-arm pacer said: "I think about it (retirement) most days. It's always on my mind.

"It is probably getting to be that time, but to be honest, I am just trying to play each game and enjoy it like I have said before."

Calling it quits after the second Australia-New Zealand Test at the Waca, beginning on Friday, shouldn't come as a surprise, Johnson said it clearly. "It could be after this game.

"I might just say 'I am done', but I'm still enjoying my cricket at the moment and enjoying the challenges. It is a really good time for Australian cricket with these young guys in the team and I want to be a part of that.

"As long as I am performing well and doing my job in the team, then I am good mentally."

Johnson feels he is still in sufficiently good shape to generate searing pace despite the wear and tear he has had, and the toll fast bowling has taken on his body. "You have your niggles here and there and just like every fast bowler, that has been before me.

"You have your little issues that you have with your body and I am no different," he said.

"That is part of being a fast bowler. You are going to be sore when you play and I like that feeling of having that soreness. It doesn't sound great, but I like that feeling.

"It feels like I am doing something out there and pushing my body to its limits. As long as I keep doing that maintenance and looking after myself after each game, then I will be right to play on."

"I feel like I'm still performing pretty well. I'd like to get a few more wickets, but I don't feel like I've dropped off too much. My pace is still up there and I feel confident about myself."

On being given the choice, Johnson said he would like to retire in Australia itself. "I'm not emotional or anything like that, because I'm not retiring right now. But it's always special playing in Australia and it does excite me.

"I started my career in Australia, played my first Test at the Gabba (against Sri Lanka in 2007). I think I'd like to finish my career here if I had the choice," he said.

Johnson admitted that he underestimated the threat New Zealand's Kane Williamson could pose. Williamson scored a brisk century to take the fight on to the Australian camp at the Gabba in the first Test, which was hugely dominated by the Aussies.

Johnson, therefore, is desperate to make amends at the Waca. "It is a bit of a surprise to me, the way he played. I hadn't seen a lot of him. I knew about him, but I didn't realise what a good player he is," he said.

Johnson said the performance of Williamson had rated highly in Australia's analysis of the first Test as they would make their plans accordingly for the second rubber.

According to Johnson, he and his fellow bowlers had inadvertently played to Williamson's strengths.

"If we can bowl on the good areas, use our bouncer to him especially on this wicket, which hopefully is going to be a bouncy one, then it will help get him out. I think it's just being a bit more patient," Johnson said.

"I think we played into his game a little bit. He's really good off the back foot as we saw and scored some easy runs through that point region, especially backward point."

The 34-year-old believes Perth provided a great venue for him to strike back at New Zealand's in-form man. "Kane can play all the shots. He looked good in defence and it is a really good challenge.

"I am really looking forward to playing him out here on a ground that I really enjoy bowling on and test myself against him," Johnson said.