Spurs find themselves top of the table for the first time in over six years, though have never sat above all their rivals this late into a campaign.
Sherwood has been impressed by Mourinho's impact at the club, the Portuguese recently marking one year in charge, and feels the whole squad have bought into his methods.
"He's found a way with the group of players he has,' Sherwood told talkSPORT.
"He's bought very well, [Sergio] Reguilon has been a good signing at left back, but [Pierre-Emile] Hojbjerg for me has been the best signing. He fits into the style and just protects the two centre halves.
"Jose has brainwashed his players to believe they have to work to achieve something – they need to win trophies, this group of players.
"When you play as solid as they do, he's almost brainwashed them into believing, and why wouldn't you believe in him?
"He's won 20 major trophies in his career and you're winning football matches, so then you start believing that this guy is the real deal, he knows what he's talking about, and why can't we win the league?"
Spurs beat Manchester City on Saturday, with Heung-min Son scoring his ninth league goal of the season and Harry Kane notching his ninth assist.
Sherwood added: "When we've got players like Son and Kane, who are world-class and could probably play in any team in the world, you've always got a chance."