Sibierski has started his Latics career in stunning fashion with three goals in his first three games to help Wigan to a surprise third place in the league.Titus Bramble, another former Magpie who moved to the JJB Stadium over the summer, has also been a key figure.
Sibierski is convinced Bramble will continue to improve and go on to play for England.
Sibierski: "He definitely needed to leave Newcastle.
"He is not the same player now as he was at Newcastle. I don't know why. Maybe it's because there is less pressure playing for Wigan.
"But it doesn't matter what the reason is. I'm very happy with the player he is now for Wigan.
"I told him last week that if he carried on playing the way he has in the first few games for Wigan then he could play for England in the future.
"It is an aim he must have because it is always a great thing to play for your country."
"He laughed. But he believed me because I am an honest guy and I am not going to tell him something like that if I didn't believe it.
"Inside he is probably thinking 'Sibi is right', and hopefully it will give him more and more confidence to play even better."