Tierney is one of Celtic’s top stars as is valued at £25m by this club.
Arsenal are keen on signing the versatile player, who usually plays at left-back but can fill in all across the back-four.
But getting a deal done is proving tricky, with Celtic stubbornly knocking back bids from the Gunners for their academy product.
Arsenal are ready to pay £25m for Tierney – but it’s the structure of the deal that is proving the problem.
The Gunners have a paltry £45m to spend on new signings this summer and want to stagger out how they pay for the Celtic man.
But the Scottish club are not impressed, and their scepticism over Arsenal’s ability to get back in the Champions League is an issue.
Sky Sports reporter Kaveh Solhekhol issued an update on the saga on the latest episode of the Transfer talk podcast.
He said: “What’s holding it up is the payment structure.
“Arsenal are proposing to play Celtic £18m plus £7m in add-ons. But too many of those add-ons, as far as Celtic are concerned, are dependent on Arsenal qualifying for the Champions League in the future, and Celtic don’t necessarily see that as a realistic prospect.
“The feeling we’re getting is Celtic feel it’s got the stage now where if Arsenal can’t afford Kieran Tierney, then it’s time for Arsenal to move on.
“It’s come to that stage where Arsenal either need to put up that £25m or just say ‘finished, we’re moving on’.”
Unai Emery was grilled about the club’s transfer business earlier this month.
He said: “We are working, the club is working with the possibility to sign some new players to help us.
“We are doing a lot of meetings with the club, with (technical director) Edu, with Raul (Sanllehi, head of football) and also with Josh and Stan Kroenke on Monday in Denver.
“We have a clear idea to sign players to help us with quality and in the positions we need.”