Arsenal manager Mikel Arteta says Kieran Tierney has been 'working like a beast', but the Scotsman will not face Villarreal on Thursday.

There was hope the left-back would be fit for the Europa League semi-final first leg in Spain, having been sidelined since February with a knee injury.

But despite his impressive form in training, Arteta thinks its too soon to risk the 23-year-old.

"He's been working like a beast every single day," Arteta said.

"I don't think he's going to make it tomorrow, but he wants to be as close as possible to the football pitch to give himself the best chance.

"We need players like Tierney. We know they are the kind of players who can make a difference in a big tie like this, but I only want to put players on the pitch who feel safe to perform.

"If it's a risk, if we're going to take a gamble, I don't think it's the right game to do it."