The Basque side beat Algeciras 4-0 in midweek to progress to the last 16 5-1 on aggregate but it is not just in the cup where their form has been good.
They have won three games in a row in La Liga and sit sixth heading into the weekend's fixtures, and a win for them coupled with a loss for Villarreal would see them sit fifth for Christmas.
"I won't think about the cup until January," Arrasate told a media conference this week.
"We next play Villarreal and they are an attractive opponent and we are evenly matched.
"All I am focused on at the moment is Granada, although it would be nice to get to the quarter-finals (of the cup)."
Sociedad have scored nine goals in their last two matches and look a fierce proposition for anyone.
Arrasate is certainly pleased with how his side are shaping up.
"In the first half (against Algeciras) we were loose, we had very little rhythm and we lacked defensive intensity," he said.
"In the second half, the team turned it up, we has rhythm and killed the tie, in the end we advanced, mission accomplished.
"The more goals we score, the more we improve our self confidence.
"We are on a very good run in the league, we've achieved our objective in the Copa del Rey and now let's see if we are able to round off the year with a good result in Granada on Saturday."
Granada's form is not as good and they were dumped out of the cup by Alcorcon.
They are mid-table in the league and have been up and down in recent weeks, with the penalty shoot-out loss to Alcorcon the hardest pill to swallow.
"I apologise to the fans because being eliminated in front of thousands of people is a disappointment," Alcaraz told a press conference.
"We are all guilty of what has happened, just as we are when we win.
"We threw it away in the first half, while in the second we were able to create many chances, but were unable to score a goal and then tried more with our hearts than our heads.
"These elimination rounds are poisoned because the opponent has very little to lose. The president told us that the cup was important and those that have failed have been us."