Michael Clarke on Friday said he was confident that Australia can regain the top spot if they play well after slipping to fourth in the world one-day rankings for the first time in three years.

The four-time world champions begin their quest to regain the lead with the first-ever one-day match against Afghanistan in Sharjah on Saturday before three one-day and as many Twenty20 internationals against Pakistan.

Skipper Clarke, 31, said he was optimistic that they can fight back.

"When we left England (in July this year) we were still the number one-ranked team in the world but because of other teams playing, we've slipped back down to four," Clarke told a press conference.

"But to me it's about playing really good consistent cricket all around the world and I know we'll get back to being number one," said Clarke.

Afghanistan braced for dream clash with Australia

Clarke brushed off speculation that he will move up the batting order, saying he had not received any official indication.

But he added: "I have made it very clear since taking over the captaincy that I'll bat wherever is best suited for the team. In this series if me batting three is the right option, that's what I'll do."

Clarke agreed Afghanistan had more experience of the pitch in Sharjah and said he was relishing the prospect of playing against the minnows.

"It's an opportunity for them to come out with nothing to lose and plenty to gain and I think it will be good cricket," said Clarke.

Clarke said once they finish Saturday's game his team will think about Pakistan, who are currently ranked sixth in one-day cricket.

"No doubt Pakistan's on my mind but our focus as a team has been on Afghanistan. After Saturday's game we'll sit down then and look at the Pakistan side.

"Pakistan also know the conditions well and these are pitches where, as the game goes on, there'll probably be a little bit more spin," he added.

All one-day matches will start at 6:00 pm local time (1400 GMT) to avoid oppressive heat in the United Arab Emirates.

"We don't really know what it's going to be like starting a match at six o'clock at night. We haven't done that before in one-day cricket. It's a lot different," said Clarke.

"You have to ask me after the first match but it's going to be a big challenge for both the teams, also for Pakistan."