Toon broke a string of poor displays by beating United 1-0 at St. James' Park, courtesy of a goal from debutante Matty Longstaff.
Magpies skipper Lascelles said: "The manager made a few changes; we know how hard a job it is for a manager to drop players and put players on the bench, but he's put Matty Longstaff in there, added Ciaran to the team and obviously Allan (Saint-Maximin) was back in the team, so a few new faces who haven't really featured this season and they did a great job.
"It was a fantastic debut for Matty - you couldn't write it - and I was pleased for him and his brother that they were playing together.
“All over the team, we were enthusiastic, energetic, in their faces. We've set our standard now and that's how we always need to play. Nothing less.
“We'll enjoy this little international break and after that, we'll start planning for another big game at Chelsea.
“I think momentum is a big thing in football but I think a little break won't do us any harm and we can refresh but still knowing that we've just beaten Man United, and we're still on a high from that, so hopefully we can go into the Chelsea game full of confidence."