Serie A giants Napoli are also keen on the left-back, and could still pip the Gunners to the race as the Hoops will crave the fattest transfer cheque possible.
Celtic have already signed Belgian left-back Boli Bolingoli from Rapid Vienna for £3 million – a clear indicator that they are ready to cash in on Tierney – and it is left for Arsenal, or Napoli, to meet their demands.
The Scottish giants value the 22-year-old around £25 million, and the Emirates Stadium club have seen their £15 million and £17.5 million bids knocked back.
The Gunners are expected to return with an improved bid, but they already have a plan B in Real Madrid’s Marcelo.
Although, it remains to be seen if the four-time Champions League winner will prefer Arsenal to other top suitors.
While Tierney remains a Celtic fan through and through, the excitement of playing in arguably the best league on the planet and also earning around £70,000-a-week starting salary in London will be too huge to turn down.