Atlético go into the high-profile game in form -- having won eight of their last nine league games -- just four points behind Real Madrid and Girona at the top of the table and level with Barça, with a game in hand.
"In the dressing room there are good vibes, a good atmosphere," Morata told ESPN.
"We feel like we can have a different year, we can fight for everything. It's what we need to do. We're Atlético and we need to always fight for every title. But this year feels and smells different.
"Sometimes, in some seasons, you can feel small differences between the starters and the players on the bench. But this year we're all together, we're tight, we're working hard and enjoying every game."
Atlético's strong start to the season has been helped by the form of Morata and strike partner Antoine Griezmann, who have scored 12 and 13 goals respectively in all competitions.
"We hope [we can win LaLiga]," Morata told ESPN. "This weekend we have a new opportunity, against one of the best teams in the world. I think they'll be thinking about this game. We're dangerous now, if we're all together we are a top team."
Griezmann -- who left Atletico for Barça in 2019 before returning in 2021 -- is now just two goals behind Luis Aragonés as Atlético's all-time top scorer.
"Time will tell if I'm a legend, if I stay in people's minds for years, the way Luis Aragonés has," Griezmann told ESPN.
"Let's hope so, because he's someone very important in the history of the club. I hope I can reach that level, or maybe the next one down."
Sunday's game at Montjuic will see Atlético face former teammate João Félix, who joined Barcelona on loan in September, and has since suggested that he didn't feel comfortable with Atlético's style under coach Diego Simeone.
"We don't think about [João Felix's comments] much, and we don't talk about it in the dressing room," Griezmann said. "He's a Barcelona player and we wish him the best, except on Sunday. In the end, everyone does what they want and what they think. It isn't for us to tell him what he should do. He's old enough."
"Some players don't feel comfortable running more when it's time to defend, João for example," defender José Giménez told ESPN.
"I like our style, it's about defensive sacrifice. Maybe he doesn't like that. He likes to be more attacking and pay less attention to the defence. It doesn't mean it's bad, it doesn't mean it offends us, it's a point of view. That's why he chose Barcelona, and we're here. I'm sure he didn't say it with any ill-will."
Barça forward Robert Lewandowski has come under pressure this season for his lack of form, finding the net in just one of his last nine club games.
"I'm a big fan [of Lewandowski]," Morata told ESPN. "I hope he doesn't see this interview before the game, for his confidence! I have big respect for him.
"When I started my career, for me with Luis Suárez and Benzema, they're the fantastic three for me in the last ten years. After that, Harry Kane has become one of the best, but I've always loved to see Lewandowski play."