Goals from Lionel Messi, Andres Iniesta and Gerard Pique gave Barca a 3-1 first-leg victory at Camp Nou on February 11, leaving Villarreal with a tough ask in the second game.
Needing to overturn a two-goal deficit means Marcelino's side will have to attack at El Madrigal, and Busquets believes that plays into Barcelona's hands.
"We're one step away from the final, and are motivated by the chance to qualify," said the midfielder.
"Yes we have a slight advantage and that changes things, it will not be like games in the league or cup so far where teams close us down and try to counter-attack. That will benefit us.
"[But] Villarreal have got a strong squad, they all deserve respect."
Fresh from cutting Real Madrid's Liga lead to two points this weekend - thanks to Villarreal's 1-1 draw in the capital - and beating Manchester City in the UEFA Champions League last 16 first leg, Barca remain in contention for three trophies this season.
History suggests hopes of a treble will not be dented this week given the Catalan giants have won their last five meetings with Villarreal in all competitions, and have not lost on their last seven trips to El Madrigal.
However, Villarreal will not be underestimated by Luis Enrique's side as their impressive campaign goes from strength to strength, Sunday's draw at Santiago Bernabeu extending their unbeaten run to four matches.
That sequence stretches back to the first-leg defeat, while their home record reads 11 wins and one draw since Valencia's win there in early November 2014.
"We can create problems for them and I hope our play, luck and skill allows us to reach the final," he said. "But we will be up against one of the best teams in the world.
"However, every game is different and we are playing at home. We'll need to defend well and attack well, but these players deserve it. I’m proud of them and we’ll give our all. Then we’ll see if the ball wants to go in."
Barca will have Pique back in contention after missing the win over Granada through suspension, while only Thomas Vermeulen is definitely out with injury.
The hosts have no new injuries worries to contend with, Antonio Rukavina (hamstring), Bruno (broken leg) and Bojan Jokic (knee) all still long-term absentees.
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