The Real Sociedad boss believes his side's form has improved markedly since their 1-0 defeat at Old Trafford and is confident of pulling off an upset
La Real sit rooted to the bottom of Group A with zero points from three games and face a huge challenge in making it out ahead of current leaders United, second-placed Bayer Leverkusen and Shakhtar Donetsk just above them.
Despite the three-time European champions' status as favourites, Arrasate insists that he has faith that his team - which finished fourth in La Liga under former manager Philippe Montanier last season - can defeat the Red Devils at Anoeta.
"We have a very important game and that if we do things the right way, we can beat Manchester United," he said. "We don’t have an inferiority complex. We want to do a good job and we are aiming to do that, and if we can, I believe we can win."
Real Sociedad has scored 10 goals in its last three Spanish top flight matches en route to two wins and a draw since it was beaten 1-0 by United on October 23, and the club's coach is confident that the gap in quality has decreased since that result.
"We've been playing better in La Liga and maybe we have reduced the difference between the two teams," Arrasate added. "I think we can play better than we did at Old Trafford. We'll try to be very tight in defense, not concede many chances and then put our chances away. They are very good on the break, they showed that at Old Trafford.
"We're doing much better, we've got two very good results, got two good victories at home and kept two clean sheets. We’re getting used to playing during the week and we’re going to try to win the game."