Mikel Merino's proposed transfer to Arsenal moved a step closer on Saturday after the midfielder was left out of Real Sociedad's squad for their opening LaLiga match.

Sources have told ESPN that Arsenal are nearing an agreement for the 28-year-old, who has already finalised personal terms with the north London club.

Talks are continuing over the exact fee and payment structure -- thought to be in the region of 28 million ($36.2m) -- and Real Sociedad coach Imanol Alguacil has confirmed Merino will not take part in Sunday's home game against Rayo Vallecano with his future uncertain.

"We worked with the idea that we would count on him, but I decided to leave him out of the squad," Alguacil told reporters in Spain.

"He told me that he was ready to help. He wanted to be on the pitch. We are the ones who are here.

"There are open talks with other clubs and this decision is the best for them, for the club and for me.

"I don't know if I'm optimistic about him. I know more or less what he wants, but we don't know how those talks will end. At the moment, he's with us. Tomorrow he'll be out of the game.

"We are talking about the best midfielder in LaLiga, as I have said before. You can imagine what that means."

Real Sociedad have been trying to tie down Merino to a new contract with his existing agreement set to expire next summer.