Less than half of the 54,000 tickets have been sold for Wednesday's friendly against fellow World Cup finalists Ivory Coast in Gelsenkirchen.
"Obviously this date at the end of the year is one of the reasons (for low sales)," Bierhoff told reporters, adding that the global economic crisis was taking its toll on ticket sales.
"People will think about spending more money shortly before Christmas," he said.
"But we must also return to the level where we offer good performances and excite the spectators also in the friendly matches we stage."
"It was right for the team to mourn... but we do not want to overload the match on Wednesday with it," said Bierhoff.
"We want to return to our everyday sporting business and enjoy play football because we love it. It would also have been Robert's wish to play with vigour in this match."
"Neuer will play in the second half in front of his home crowd," Bierhoff said. Bayer Leverkusen striker Stefan Kiessling will also be in the starting line-up.
