The Basque outfit beat Getafe on the opening day but went seven games without a league win before edging out Valencia 2-1 and defeating bottom side Almeria 3-0.
Arrasate, who replaced the Rennes-bound Philippe Montanier in the summer, knows Valladolid can be a tricky proposition at their Jose Zorrilla base and is demanding maximum effort from his players.
He told a press conference on Tuesday: "The most important thing is tomorrow's match. We have claimed two victories and want to make it three. That's hard to do in La Liga.
"We understand that if we can win tomorrow then we'll have taken another step further and we're only thinking about doing that.
"We have to get it right, though, and Real Sociedad will have to be at their best to get the win."
Defender Dani Estrada and midfielder Gorka Elustondo have travelled to the Castile and Leon region with a view to passing late fitness tests and representing Sociedad.
Valladolid secured an impressive 3-0 victory at Rayo Vallecano last time out, but soon suffered a setback when it emerged Manucho had cracked a metatarsal in his left foot during the game.
The Angolan former Manchester United striker will be unavailable for at least three weeks while defender Heinz Barmettler and midfielder Victor Perez struggle for condition.
The win in Madrid was only a second of the season for Juan Ignacio Martinez's side and, although he can see promising signs of improvement, he will be disappointed if his players fail to dominate Sociedad on home turf.
"We are happy but we cannot ignore reality," the Valladolid coach told Marca. "We went into that game knowing we needed to win, given the run we'd been on.
"We played a good game, taking a little step forward in terms of aggressiveness and forcefulness, and we're managing a bit better against opponents in the middle of the park."