Also, I think defeating Manchester United was not a big deal for Tottenham. You should be saying this if Tottenham had beaten teams like Arsenal or Manchester City or even Chelsea. Who is Manchester United this season for winning them to be a great achievement? Many clubs in the EPL now can win Manchester United. And when i mean by many clubs i mean, underdogs team.
Actually, it's not too special if we look at their opponent, Man United, it's like that, what more can we expect. And previously, Tottenham also couldn't beat Arsenal and Newcastle. It's just that, we know how Man United is, even though they're not that good, but they're still always considered a big club. That's why when Tottenham beat Man United, it felt very special. But you're right, we are still waiting for the next big matches again to see if Tottenham has really increased significantly well or not. 
Source: Manchester United
Anyway about Man United, in the final Man United won the appeal against the red card received by Fernandes. See this will really chance the performance to be better again?