The Netherlands star is disheartened that three important players are ruled out already ahead of a challenging part of the campaign for the Bavarians
Mario Gotze, Thiago Alcantara and Javi Martinez are still suffering from injury and have been ruled out for the encounters against Hannover on Saturday and the first Champions League clash against CSKA Moscow on Tuesday.
And the 29-year-old feels it is going to be challenging to compensate for those losses in the upcoming weeks.
"Now it begins," the Dutchman told reporters on Thursday.
"We need all our players. It's a pity that three important players are ruled out already."
The Bavarians have recently presented the team's new away jerseys for the 2013-14 season, which are inspired by traditional Oktoberfest outfits.
"I hope that we will be able to win our first game in the new jerseys," Robben added.
Bayern face a heavily congested fixture list, with seven games coming up between September 14 and October 5 before the international break.