After playing a pivotal role in the 4-1 win, the Arsenal youth product admitted he was pleased to get a chance on the big stage.
"It was obviously a big thing for me to start here tonight and to show what I can do. To come in against our rivals and score is a dream," Lansbury told arsenal.com.
"Coming here [and playing] is massive. I've had all my mates on the phone today saying 'Are you starting? Are you starting?'
"Obviously I'm pushing for a place every week, that's why I want to be in the first team. I've just got to keep working hard in training and hopefully I'll get my chance.
"It was good to get on the score sheet and it was a great performance from our team.
"Coming into a London derby is a great experience. Seeing the tempo of how the first team play - I just want to get involved in that.
"To come here and win is always a great time for the fans. We put on a show tonight for them."