Tottenham completed the 18-month loan signing, with an option to buy, of Fernandes from Benfica.
It raises questions about how Mourinho will fit all his midfield players into his team and whether Winks will warrant a place.
Durham said: “Gedson Fernandes is, not a similar type of player, but will play in a similar position and is actually more a Mourinho type player.
“He’s actually a Mourinho version of Harry Winks, that’s how I see it. He’s not going to get him in and not play him, is he?
“He seems to be disillusioned with Ndombele and I’m not quite sure Mourinho is convinced about Harry Winks, which is why Fernandes has come in, in my opinion.
“Defensively, I think he’s still trying to get his defence right but I think in front of his defence he needs the right players as well and to me it’s that physical presence.
“Gedson Fernandes, when fit, is going to be a starter for Tottenham Hotspur. That’s the way I see it.
“It’s whether there’s room in that midfield for Harry Winks alongside him. And if there isn’t, what does that mean for Winks in terms of England and Euro 2020 because a few months away there is a massive tournament with a lot of games on home soil.”
Durham also questioned whether Winks had the quality to play in a team like Tottenham.