Aaron Ramsey's first-half goal was backed up by a late clincher from Lacazette, with the win moving Arsenal ahead of local rivals Tottenham and into third place in the Premier League with just seven games left to play.
Arsenal were ten points behind Tottenham only last month, yet Lacazette believes the momentum is on their side after a collapse from Spurs that has seen them collect just one point from a possible 15 in their last five Premier League matches.
"I can feel the difference in the atmosphere from last season, now we can maybe go to the Champions League," said Lacazette. "The fans helped us to get third place. We work every day to be in third place, now we must stay in this position.
"It was a big game tonight, a tough game. The coach said we had to be patient and efficient in the box and we did that.