Fifth bowling option a concern for Langer

Coach Justin Langer admits the absence of Marcus Stoinis is "problematic" for the balance of their side, as Australia continue to sweat on the fitness of their key allrounder.

Mitch Marsh has flown into London to join the squad as cover, but Australia are waiting to see if Stoinis can overcome the left side strain he suffered while bowling in their defeat to India on Sunday.

In a positive sign, the 29-year-old batted extensively in Taunton's indoor nets on Wednesday, but bowling remains off-limits. A return for Saturday's match against Sri Lanka at The Oval appears unlikely, but Australia then have a five-day break before their next game against Bangladesh.

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The lack of a back-up seam-bowling allrounder in their 15-man World Cup squad (Marsh cannot play unless Australia are prepared to rule Stoinis out for the tournament) left Australia in the lurch against Pakistan, forcing captain Aaron Finch to rely on Glenn Maxwell and himself to make up the balance of the fifth bowler's overs.

Finch claimed the key wicket of Mohammad Hafeez with a full toss, but he and Maxwell conceded 71 from a combined nine overs.

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"We've talked a bit about it, but we'll just see how he pulls up over the next few days," Langer said of Stoinis.

"We know that it's important to have an all-rounder in the side if we can and if we can't we've got to adapt but we'll just have to see how he pulls up."

Stoinis has had a lean recent run with the bat, failing to pass 20 in his past six hits, but his overs have been increasingly important and is often entrusted with death-bowling duties. Ricky Ponting, the Australian World Cup winning captain and current assistant coach, also rates him as the side's best boundary fielder.

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Finch earnt praise for his tactical acumen in Stoinis' absence from the likes of Ashes-winning former England captain Michael Vaughan.

His gamble of bowling Pat Cummins his full allotment before the 40-over mark and then bringing Mitchell Starc back early to knock over the tail paid off as Australia claimed a tenser victory than the margin – 41 runs – between two sides' suggested.

But it could have backfired had Pakistan taken their run chase a little deeper.

That would have left one of Maxwell or Finch having to a bowl a high-pressure over at the death at a venue with short straight boundaries.

"We're going to have really tighten up that area," Langer said of the fifth-bowling issue. "This is a very, very small ground. There's no margin for error – if you overpitch, it goes for six. We were targeting (their part-time spinners) as they probably were as well.

"We'll have to work it out, but it certainly makes it more problematic not having an allrounder in there.

"It's probably harder for Finchy than anyone else to have less recognised bowlers. Everyone's got to be on top of their game."

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If Stoinis isn't fit to play on Saturday, Finch will likely be faced with the same issue for the Sri Lanka game as the one he had against Pakistan.

The bigger boundaries at The Oval though could be a godsend in that regard and could open the door for leg-spinner Steve Smith to send down some overs, something 1987 World Cup-winning captain Allan Border has called for.

Another option could be to play five specialist bowlers and bump wicketkeeper Alex Carey up to No.6 and Nathan Coulter-Nile to No.7, with both having made impressive lower-order contributions in the tournament so far.

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It's a strategy Australia tried during their limited-overs tour of the United Kingdom last year in Langer's first series in charge, but the coach isn't convinced it's a sustainable option in ODI cricket.

"It's very rare for an Australian cricket team to do it," Langer explained. "You see it in domestic cricket a bit, but I think domestic cricket's a bit different than international cricket particularly with the wickets we play on, with the skill we play against, the talent we play against.

"We could do it. We did it a few times last year when we were in England.

"It's tougher in 50-over cricket but you never say never. We'll try and work out the best combination is to beat Sri Lanka."

2019 World Cup

Australia's squad: Aaron Finch (c), Jason Behrendorff, Alex Carey (wk), Nathan Coulter-Nile, Pat Cummins, Usman Khawaja, Nathan Lyon, Shaun Marsh, Glenn Maxwell, Kane Richardson, Steve Smith, Mitchell Starc, Marcus Stoinis, David Warner, Adam Zampa

June 1: Australia beat Afghanistan by seven wickets

June 6: Australia beat West Indies by 15 runs

June 9: Australia lost to India by 36 runs

June 12: Australia beat Pakistan by 41 runs

June 15: Sri Lanka v Australia, The Oval

June 20: Australia v Bangladesh, Trent Bridge

June 25: England v Australia, Lord's

June 29: New Zealand v Australia, Lord's (D/N)

July 6: Australia v South Africa, Old Trafford (D/N)

July 9: Semi-Final 1, Old Trafford

July 11: Semi-Final 2, Edgbaston

July 14: Final, Lord's

Sync Australia's World Cup schedule to your calendar HERE

For a full list of all World Cup fixtures, click HERE