Tottenham won the game 2-0 thanks to goals from Alli and Ben Davies but after the game, the only thing anyone was talking about was the red card.
Alli has often been criticised for his temper but Pochettino had nothing but praise for the former MK Dons man following Sunday's win.
"He was calm - that's important," Pochettino said. "Last season, we talked a lot about that, how we need to behave and improve and learn.
"He's mature enough now to accept sometimes what happens on the pitch, but he is so calm, he is so brave. Then he scored - a great goal - and I am very pleased.
"I think it was clear it was a red card. The referee has seen the action, it was very clear. It's unlucky for Newcastle. I'm sure Rafa is upset about the situation. Sometimes when you're a player on the pitch it's not easy to have the control."
Alli, for his part sympathised with Shelvey, the 21-year-old midfielder told 'Sky Sports': "It's one of those things but he's a great player and I'm sure he's going to be disappointed. I've been caught out a couple of times for my temper but it's something I like to keep to my game.
"It was a game where we had to keep our cool, we didn't want to get too heated up and get brought into what they wanted us to do, which was make it more of a physical game and a battle than a game of football.
"It was important that we just kept the ball moving, I don't think there was any need to react today. I was happy with the performance and the win."
Has Alli turned over a new leaf? Or will the 'devil' in his play come out an some inopportune moment later in the season?