Arsenal have had two offers rejected by Celtic as they continue to pursue Kieran Tierney .
Unai Emery wants the full-back at the Emirates next season but the Gunners hierarchy have been unable to terms with the Premiership champions.
An initial £15m offer was rejected out-of-hand and a second approach worth £25million also failed to make the Hoops budge.
The latter offer involved a series of add-ons, largely dependent on appearances, instead of a straight fee.
And it's been reported on Sunday that Celtic were particularly unconvinced by one aspect of the bid.
Sky Sports report it included incentives based on Arsenal qualifying for the Champions League - something the Parkhead club are said to be unsure is realistic.
Emery's side reached the Europa League Final last term but failed to qualify for the big one - missing out to rivals Tottenham Hotspur by a single point.
The Premier League's race for the top four is getting tighter and tighter every year, with Manchester City and Liverpool well out on their own at the top.
But Chelsea, Spurs, Arsenal Manchester United are all vying for the final two places at Europe's top table in the coming season.
Arsenal are reportedly confident they can get a deal over the line and talks are expected to continue.
Tierney is currently recovering from a double hernia operation and a pelvic issue that has resurfaced.
He faces a fight to be fit Celtic's Premiership opener against St Johnstone on August 4, having not featured at all for Neil Lennon's side in pre-season.
