Wigan boss Roberto Martinez accepts that Charles N'Zogbia's profile continues to rise, but he has no plans to cash-in on the in-form winger.[LNB] The Frenchman returned to haunt former employers Newcastle on Saturday, bagging a brace as Latics played out a 2-2 draw at St James' Park.[LNB]N'Zogbia's impressive showing has once again led to reports that he could soon be on his way to pastures new, having spent much of the summer embroiled in transfer speculation.[LNB]A £9million switch to Birmingham collapsed at the last minute, as deadline day approached, and the 24-year-old ended up sticking with Wigan.[LNB]Martinez is delighted to still have the tricky playmaker at his disposal and admits that he will be reluctant to part with N'Zogbia during the winter transfer window.[LNB]"Charles' value will go up because he is only 24 and playing for the national team," said the Spaniard.[LNB]"But he's someone we don't want to lose."[LNB]Martinez has also revealed how he was happy to hear the Newcastle supporters berate their former star over the weekend, with N'Zogbia having matured into a player who thrives in a hostile environment.[LNB]He added: "Last season Charles took his ability to another level, and this season he has carried on. He's improved a lot.[LNB]"He understands why he would get a bad reception here (Newcastle), but he's got experience and he sees it as a compliment.[LNB]"It makes you feel like you're a threat, someone who hurts the opposition.[LNB]"You could say I was happy to hear the boos. It drew a reaction from him. We knew how the Newcastle fans would react and he relished the challenge."