Australia's knack for grinding out wins despite not playing at their best is helping them build momentum for a strong tilt at the World Cup title, former skipper Allan Border has said.

Defending champions Australia beat Pakistan by 41 runs in Taunton on Wednesday to seal their third victory in four games at the tournament, with their only defeat coming against India on Sunday.

A struggling middle order and a lack of support for the main pace duo of Mitchell Starc and Pat Cummins have emerged as Australia's main concerns in the early days of the World Cup, but the team are currently second in the overall standings.

“Australia aren't playing at their best but they are winning matches. That's the way I saw the win over Pakistan,” Border wrote in a column for the International Cricket Council.

“In the early stages of the World Cup, you want to be right amongst the pacesetters after four rounds and Australia very much are.

“They are building nicely and all the teams will feel the total package is still in them. They'll talk about being relentless and consistent... and they can create momentum for some of the big teams they still have to play.”

Border added that Australia should consider using Steve Smith to shore up their bowling attack and backed the 30-year-old to use his leg-spin to good effect.

“The fifth, and even the fourth, bowling option is looking like a slight concern for them,” Border said. “I think they should look at Steve Smith having a bowl, I really do.”

“Leg spin takes wickets and whether it's Adam Zampa coming back in or Smith trying a bit of his spin, that should improve the attack dramatically.”

Australia next play Sri Lanka at The Oval in London on Saturday.