YORKSHIRE must get by without Aaron Finch "for up to 12 weeks" and Ryan Sidebottom for six after latest injury updates on the pair.

Destructive opener Finch has had surgery on his hamstring - and after a scan last week, the length of veteran left-arm seamer Sidebottom's absence has also been confirmed.

Australia can still expect Finch to be fit in time for their limited-overs series against England, beginning with a one-off Twenty20 match at the end of August.

But his availability for Yorkshire is a different matter and he seems certain to miss the vast majority of their NatWest T20 Blast campaign.

Yorkshire were hoping, even when Finch conceded he would have to sit out the remainder of the Indian Premier League after suffering the injury earlier this month, that he would be able to join them by the end of May.

But today's statement from Cricket Australia (CA) has ended that prospect and the likelihood is Finch will not be ready until the Blast knockout stages - should Yorkshire progress that far.

A CA press release explained Finch underwent surgery on his left leg in Melbourne yesterday.

CA physiotherapist Alex Kountouris said: "After returning to Australia injured from the IPL, Aaron had scans that confirmed a high grade hamstring injury. As such, Aaron was assessed by a surgeon who felt that he would have a better outcome with surgery.

"Aaron subsequently had surgery yesterday that has gone well. He will now commence his rehabilitation and we expect that rehabilitation to take up to 12 weeks."

Finch himself sounded optimistic on Twitter post-operation, telling his followers: "Finished up having surgery on my hammy. One night in hospital but it all seemed to go very well."

Yorkshire have already had to change their plans for overseas players once this season, recruiting Cheteshwar Pujara to help in their LV= County Championship defence after Younus Khan became unavailable because of international commitments.

Finch's fellow Australia World Cup winner Glenn Maxwell is still on course to join them, after the end of the IPL next month, and New Zealand batsman Kane Williamson is due to arrive again for the latter stages of the County Championship summer.

Sidebottom hurt himself running between the wickets in Yorkshire's opening Division One match, which they won at Worcestershire.

The 37-year-old former England bowler has a grade two tear to his left calf and has already begun a rehabilitation programme.

Yorkshire physiotherapist Kunwar Bansil said: "It is a great shame for Ryan. We will monitor his rehabilitation on a daily basis and hope that he will return to cricket in six weeks."

Yorkshire had to begin the defence of their county crown without seven first-choice players - captain Andrew Gale, who was completing a disciplinary ban at Worcester, and six away on Test duty with England in the West Indies.

They are reportedly considering whether to ask England if leg-spinner Adil Rashid, still uncapped after missing out on selection for the first two Tests, can return home early to bolster their squad.

Yorkshire are hoping to sign a replacement to cover Finch's absence.

Director of cricket Martyn Moxon said: "It is disappointing news for Aaron and for us. We were hoping he would be with us in May but that is not going to happen. Plans are in place to fill the void that Aaron will leave.

"We hope we can get this sorted sooner rather than later and remain confident we'll find a replacement for the LV= County Championship and the NatWest T20 Blast."