Goals from Aaron Ramsey and Alex Lacazette made it 10 straight Premier League victories at Emirates Stadium, but the shutout against Newcastle also saw Arsenal record three consecutive clean sheets for the first time since December 2017.
“I think from the first minute to the last minute it was a concentrated performance from us," Leno told Arsenal.com.
“It was very hard because Newcastle play very deep but their whole team and then we scored the goals and it was a well-deserved win.
“We had to keep calm because Newcastle were waiting for one chance from a corner or a free-kick to score and then it's more difficult to score a goal and win, so I think the first goal was very important for us. We kept possession and kept playing the ball, which was the main reason we played so good."
Monday's win takes Arsenal up to third in the league but Leno knows there's plenty of work to do to secure a Champions League spot.
“I think we're in a very good position but it's still a long way because the other teams will wait for our mistakes," he said. “We have to be focused in every game and if it's possible we need to win every game. Then we can get back to the Champions League."