"We want to go at Manchester United because they are one of the best European teams at the moment. We want to show that we didn't escape the drop by chance, that we are capable of getting a result against this type of team."
Sibierski slammed those who have hinted that Wigan might not give it their all.
"It makes us smile a bit," added the 33-year-old. "But we also have the impression that we are being taken for idiots. Especially when I hear (Chelsea midfielder) Michael Ballack say 'I hope the Wigan players won't be on holiday already'.
"We are professionals. It's a game that will be followed throughout the world. It's important not to be ridiculed. We're playing against some of the best players in Europe. It's the kind of match that everyone in the world wants to play in and certain players have the desire to show what they are capable of.