Sociedad have been handed a tough draw and should be able to take a narrow lead back to San Sebastian.
Real Sociedad restricted Barcelona on Sunday night as they continued their fine La Liga form.
Valladolid are unbeaten in 5 home games in all competitions
Bet365 make Valladolid 13/5 whilst Sociedad can be backed at Evens
These ties are played over two legs which is handy for Real Sociedad as this won't be an easy place to pick up a result.
They arrive in tremendous form though and as tipped on here, they held Barcelona to a draw. They restricted the chances and space for Lionel Messi and co and came away with a much deserved point.
They are just four points behind Luis Enrique's side and sit in 5th place, looking menacingly up at the rest of the top four.
As the form team in La Liga, they will be expected to get the job done here, but it won't be straightforward. They will have to do it without Imanol Aggiretxe, who didn't train earlier in the week due to a knock.
They've won their last two games against Leganes and Gijon and a narrow margin victory to take into the second leg would be ideal.
The hosts are winless in three, but did play out a goalless draw here at the weekend. They currently sit in 14th place with mixed recent form. Just a single win in five isn't ideal, but they have been reasonably solid at home.
The Spanish second tier is incredibly close and although they sit midway down the bottom half, they are only four points off the play-offs.
Back Real Sociedad with a 1 goal winning margin at 13/5 with Bet365
Take a 1-0 scoreline to the visitors at 5/1 and have a look at Draw/Sociedad on the HT/FT market at 15/4 with Bet365