49ers' RB Jeff Wilson Says He Loves SF's Doubters, We're Using Hate As Fuel!

Stud running back Jeff Wilson says the Niners are LOVING the shade doubters are throwing their way after their 3-0 start ... he tells TMZ Sports SF's using it as motivation!!!

"It's cool," Wilson says ... "That can continue to be our fuel."

The Niners are off to a piping hot start this season ... but with their trio of wins coming against the Buccaneers, Steelers and Bengals -- people aren't quite sold on them yet.

When we spoke with Wilson -- he told us he's fine with that ... saying it'll "continue to motivate us."

But, Jeff tells us he's also trying not to pay too much attention to any of the outside noise ... saying the Niners have a great locker room that doesn't need outside validation.

"We just going to keep on working on ourselves, man," Wilson says.

"And, just going out and playing every Sunday and leaving it all on the field and whatever else anybody got to say or feel their opinion is, it'll be that."

The Niners have a chance to shut up some of the doubters on "Monday Night Football" against the Browns ... a lot of people would consider that a huge win for the Bay Area squad.

As for Wilson's personal game on the field ... he's killing it this year with 4 TDs on just 18 carries -- and he tells us fantasy owners everywhere are LOVING him!!!