The Gunners have been in discussions with Sociedad for the 28-year-old for the past few weeks and they have now sealed the deal.

Mikel Arteta 's side will pay around €32m up front for Merino with a further €5m in the form of performance add-ons.

The Spaniard has already agreed personal terms over a long-term deal and he is expected to travel to London for his medical tomorrow.

The Gunners take on Aston Villa in the Premier League on the road on Saturday. It seems unlikely that he will be registered on time.

Merino may have to wait until August 31 when the London giants host Brighton & Hove Albion at the Emirates Stadium.

The former Newcastle United man should be a fine signing for the Gunners, considering his strong defensive and creative skills.

Merino won the most number of duels in Europe's top-five leagues last season and contributed towards 13 goals for Sociedad.

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