Agent Kieran Tierney is Arsenal secret weapon and Real Madrid know it as he aims to right a wrong against Mbappe

Kieran Tierney only spent 12 months in the Basque country on loan to Real Sociedad from Arsenal.

But in that time the former Celtic captain could pack a dossier of knowledge on Spanish football - and it could be used to bring down Real Madrid this week.

The full-back will travel with his Arsenal team to defend their 3-0 lead over Los Blancos after a stunning Champions League performance at the Emirates last week.

Tierney came on in the last 10 minutes, as a winger, to see the result through and revelled in the on-pitch celebrations at full time.

His week got even better as he was given a starting berth in the Premier League match against Brentford, but a narrow offside denying him a dream goal.

Tierney will be willing and ready to step in where he can for Mikel Arteta and see the Gunners into the semi-final - and he knows exactly who to ask on how to disrupt the Bernabeu cauldron on Wednesday night.

Coach Imanol Alguacil has been at Sociedad since 2018 and won the Copa Del Rey in 2020 over derby rivals Athletic Bilbao, who face Rangers in the Europa League on Thursday night.

En route to that cup triumph La Reale won a 4-3 thriller in Madrid with Arsenal teammate Martin Odegaard and Newcastle striker Alexander Isak doing the damage on the night.

Fast forward to this month and Alguacil's men caused havoc at the Bernabeu in their Copa Del Rey semi-final second leg.

Blue and white shirts swarmed the home side for 90 minutes but, in typical fashion, the La Liga champions snatched a late equaliser to go through 5-4 on aggregate.

The Scotland international's one appearance at the Bernanbeu came in a Sociedad start in 2013, who pushed Carlo Ancelotti's men all the way in a 2-1 La Liga defeat in the Spanish capital.

Despite the