Melbourne- Publicly labelled "soft" by former test bowler Shane Warne only a few months ago, paceman Mitchell Starc has come of age at the cricket World Cup and could prove key to Australia's hopes of winning a fourth trophy.

The 25-year-old left-armer currently leads the wickets tally at the tournament with 16 scalps at the end of the pool phase, one ahead of a clutch of bowlers with 15, but with an eye-popping average of 8.50.

Once known as the "lesser Mitchell", Starc has put Australia's most feared strike bowler Mitchell Johnson firmly in the shade, the fellow left-armer taking a modest nine wickets at an average of 22.66.

"The ball's coming out nicely. I can't complain. It's coming out consistently well, but more importantly we're winning games," Starc said in comments published by The Australian newspaper. "That's all that matters.

"I've been working on different plans, whether that be in training or in a game, and it's nice to see them coming off."

Starc's form at cricket's global showpiece has elevated him to the most lethal wicket-taker in the one-day game.

The Adelaide Oval has one of Australia's slowest pitches, particularly since its redevelopment as a venue for Australian Rules football matches, but Starc's pace, bounce and variation could prove a handful for Pakistan when the teams clash in the quarter-finals on Friday.

Starc has set the tone for Australia's campaign, capturing the team's first World Cup wicket in the opener against England when a flustered Moeen Ali tried to pull a short ball only to be beaten for pace and caught at mid-on.

He all but bowled out New Zealand with a six-wicket haul that dragged his team into the match after they were skittled for 151 in Auckland and appeared ripe for humiliation.

His ability to swing the ball both ways and into right-handed batsmen has prompted comparisons with Pakistan great Wasim Akram.

Straight-shooter George Bailey, who led Australia against England before making way for regular captain Michael Clarke, said Starc was "more feared" as a 'death bowler' in the final overs than either of South Africa pace duo Dale Steyn and Morne Morkel.

Only a few months ago, however, Starc was making headlines after outspoken pundit Warne remarked that he looked "a bit soft" when struggling for line and length on a baking, hot day during a test match against India in Brisbane.

For a sporting country that values toughness above all qualities in elite sport, there are fewer criticisms more scathing than the 'S-word' and Warne was moved to clarify his comment after a subsequent media storm.

Competing with a bull-pen of fast bowlers for the third seamer spot behind Johnson and Ryan Harris, Starc has struggled to cement his place in tests, being picked for one match then tossed out on a number of occasions.

His 15 matches have yielded 50 wickets at a modest average of 35.44.

He was dropped after the "soft" effort in Brisbane, but returned for the final test against India in Sydney and took five wickets for the match.

Before the test he said he wasn't "losing sleep" over Warne's criticism.

But in a neat piece of symmetry, his first wicket in the Sydney match -- having India opener Murali Vijay nicking behind -- happened with Warne behind the microphone for the host broadcaster.

Warne praised the bowler and has since jokingly claimed credit for his brilliant form.

Starc has since let his work on the pitch do the talking. 'Soft' won't be the first word thrown around when Pakistan's brain trust convene to prepare for Friday's match.