Spurs currently sit top of the Premier League, having taken 20 points from their opening nine games, including wins against both Manchester clubs.
They take on fellow contenders, Chelsea, this Sunday.
With a flying start to the season under their belt, Lucas is adamant that the Lilywhites are good enough to compete with the likes of Liverpool at the top of the Premier League.
"We are building a very good mentality for the season and we made very good signings in the summer," he said.
"We know how difficult it is but why not to think to win the Premier League?
"We have the capacity to win. Every game that we play, every time we are on the pitch, we need to think we are able to win the Premier League."
The Brazilian, who joined Spurs from Paris Saint-Germain in 2018, has started just four league games so far, netting once, but is part of an attacking roster that would strike fear into every defence in Europe.
Both Harry Kane and Son Heung-Min have started the season on fire, and Mourinho has managed to find a system that brings out the best in both flying forwards.
In fact, it's the impact of Mourinho that gives Lucas so much confidence in Tottenham's potential this season.
"Mourinho wants to win a trophy here. He knows we are capable of winning. We have all that we need to win," Moura continued.
"He’s the right man to bring us to the trophy. We just need to trust in him and believe in ourselves.
"Now is the time. We have a great manager, we have great players and we need to speak about this."
With Manchester City faltering, and Liverpool's injury list containing several starters, this could well be the year for Spurs to break their trophy duck, something Lucas is hoping for.
“I have a very good feeling about this season. We need to think of every game like a final.
"We need to believe and trust in our team, our club and believe it’s possible because in football everything is possible.”