A big-money signing from Borussia Dortmund in 2019, the 23-year-old has become frustrated at the lack of starts he is making under Thomas Tuchel.
The looming winter World Cup has sharpened Pulisic's focus and he is reported to be of interest to a variety of clubs, from Manchester United and Newcastle to Atletico Madrid and Juventus.
The US captain could still end up staying put and Berhalter believes he will come good even if he remains with Chelsea until the tournament gets under way in Qatar.
"He's a fighter," the USA manager said at a Major League Soccer event. "You're going to see. He's going to get on the field.
"I mean, every year it's 'he may not be a starter', right? Every year you hear that and every year he ends up on the field because of his contribution.
"He's a goalscorer, he's a winner. What I've seen from him in the last couple of years is his mentality has completely shifted and he embraces stuff like this.
"He's not scared of challenges like (he has at Chelsea) and I'm excited to see how he performs this year."