The Parkhead club are braced for offers for the 20-year-old this summer with Premier League sides Bournemouth, Manchester United and Tottenham Hotspur all credited with an interest.
Muaricio Pochettino is expected to be in the market for a new left-back with Danny Rose strongly tipped to leave north London after struggling to regain his first team place following injury and Tierney is a key target.
And now Diego Simeone's team have also burst on to the scene and will send their representatives to monitor the player in Celtic's final against Motherwell on Saturday, according to BBC Scotland.
The 20-year-old Scottish worldwide embodies everything that the Hoops are striving for and by relinquishing that, after a report in The Scottish Sun suggested that Atletico Madrid were the latest to show an interest in the left-sided defender, would be a massive show of weakness.
The Sun is reporting that Atletico have entered the race to sign the Scotland worldwide ahead of the 2018 summer transfer window.
Tierney scored four goals and had 11 assists to his name this season which, despite suggestions he has not recaptured the heights of 2016/17, is an improvement on his figures.
The Celtic starlet has also got vital Champions League experience under his belt and has made a total of 27 appearances in Uefa competitions in his fledgling career so far.
- Mayawati Behind Hurriedly Stitched Alliance of Congress, JD-S in Karnataka
- Droom raises $30 million in Series D round funding
- Police release witness accounts in Vegas shooting massacre
- Ravi Teja Nela Ticket Movie Official Trailer Out
- VA-11 Hall-A coming to PS4 and Switch
- GTA V has sold over 95 million copies worldwide
- AT&T and Verizon will carry the RED Hydrogen One
- Raymond James & Associates Lowers Holdings in Intrexon (NYSE:XON)
- Founders Edition GTX 1180 reportedly set to launch in July
- Acacia Communications (NASDAQ:ACIA) Shares Bought by Guggenheim Capital LLC