Koeman stated that he did not see his side as favourites for the competition, despite being on good form.
"I don't think so," he replied when asked if Barcelona were favourites. "It doesn't depend on a team's recent form.
"Real [Sociedad] had a great start to LaLiga Santander. I've seen several of their games and they seem to me like one of the best teams in the division.
"For me there is no clear cut favourite to win the Supercopa.
"The four teams participating have the mentality of doing their best to win a title. All four of us have a chance, as do we.
"We want to continue with the image that we've been displaying lately.
"The team is growing. It is an opportunity to show that we are in a good way."