United will secure a 10th Premier League crown - and a 17th league championship - if they beat Wigan at the JJB Stadium as their goal difference is vastly superior to that of Chelsea, who play Bolton.

Speculation has been rife that Wigan, who secured top-flight safety last weekend, might not give 100%, especially as they are managed by Old Trafford legend Steve Bruce.

But Sibierski - a former Manchester City and Newcastle player - is shocked that the players' integrity has been called into question.

"It's difficult for me to understand," the French forward told L'Equipe. "How can people think that the Wigan players will take their foot off the gas?

"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.

"It's true that the pressure that Fulham, Reading and Birmingham still have has gone for us.

"We are safe so we are free.

"But generally, it's at that point that you begin to play your best games."