The Magpies were able to get a 2-0 win in the semi final first leg at the Emirates Stadium on Tuesday.
Despite the tough game away from home, Isak and Anthony Gordon’s goals got them a valuable lead.
Post-game, Isak told ITV: "It's massive. it's a great result. It's only the first half. If we don't go through then this has no meaning. It's a massive win.
On his own form, he added: "I don't think it's too much of an individual thing, it's more a team thing. We've been very consistent to create chances.
On the push on Martin Odegaard before the goal: "It's part of the game, we all play on the edge. It's nothing.
On what's changed with the team, he finished: "It's difficult to put a finger on but we've found out way back to our identity and the basics. It starts with how we defend. the defence and the midfield put their body on the line."