Cricket World Cup: 'I haven't been this fit in five years' - Clarke

Michael Clarke of Australia. Photo / AP

Australian captain Michael Clarke says he is the fittest he's been in five years as he looks ahead to an arduous week of cricket and long haul flights.

Clarke's long-term back injury makes long flights difficult and he has previously experienced flare-ups soon after arriving in far flung destinations.

However, after completing a lengthy recovery from his hamstring injury, the 33-year-old batsman believes he can perform against Afghanistan and back up again four days later when Australia meet Sri Lanka in Sydney.

"I feel as fit and as healthy as I've felt in five years," Clarke told Sydney's Daily Telegraph.

"That's a real positive sign. I've got no idea (how playing after the long flights will be), I've never done it before. I'm about to find out.

"Obviously a seven and a half hour flight, it does take some time to recover.

"I've got to keep my maintenance up, keep listening to the medical staff and doing as they ask because I feel like it's helping me at the moment that's for sure."

Before Clarke underwent hamstring surgery, there was talk about resting him from the Perth match - given he broke down there at the start of the summer in the first one-day clash against South Africa.

He also experienced problems upon arriving in Zimbabwe last year and when he touched down in England for the 2013 Champions Trophy - where he was ruled out for the entire tournament.

But after so much time on the sidelines, he needs time in the middle, and will look to cash in against the minnows in Perth.

Clarke indicated Australia wouldn't be overreacting about losing to the Black Caps, and coach Darren Lehmann has emphasised the importance of not looking too far ahead.

"Boof made it pretty clear to us today that he wants us to stay focused on what's right in front of us this game and we'll worry about Sunday after tomorrow's game," he said.

"We got beaten by a very good team on the day. That's the game isn't it? It's always tough to beat NZ in their own backyard.