Goals from Perez, Maddison and Hamza Choudhury ensured a vital away win for the Foxes.
Steve Bruce will be bitterly disappointed with his side’s performance and Lejeune, in particular, will have let him down.
The 28-year-old Newcastle defender was responsible for the first two goals and Newcastle had a mountain to climb after that.
Lejeune’s poor pass across the area was intercepted by Perez for the first goal and Maddison took advantage of another poor pass from the Newcastle man for Leicester’s second.
The defender will be highly disappointed with himself and it will be interesting to see how he reacts in the next game.