You didn't mentioned the full fact:
They saw their rivals Arsenal crumble in the Derby against the Blue side. Then they followed it up with a win over the arch-nemesis - United, in a win that seemed like eternity to occur.
As for the match, I'm pissed at United's first half. Giggs was non-existent. Nani was woeful in defense. The central midfield contained absolutely no physicality. And Ferdinand was dreaming.
Tottenham deserve its victory; based on their first half and their tactical discipline in 2nd half. United were way too lethargic on the first half as I said and it showed with both goals; especially Vertonghen's one. Sandro and Dembele showed us what United cruelly lacks in midfield on the first half.
Rooney did an excellent entry and brought the much-needed support in the midfield as he replaced the complacent Giggs. His cross for Nani was excellent as United tried to trigger a comeback. But we got excited in the proceedings and Tottenham nailed their 3rd goal on counter. We kept dominating afterwards.
Kagawa quickly pulled another one. Rooney was unlucky with his free-kick on the post. Got numerous chances but the defense of Tottenham were better held as minutes passed and fatigue grew up on us.
United did a great 2nd half. It's just shameful that we did an equally bad first half. Also, we were a bit unlucky. Lots of saves by Friedel, 2 woodwork and 2 possible penalties ruled-out. A draw will have been well-earned but Tottenham's victory was also well-deserved if we go by their dominance in 1st half and discipline in 2nd half. Had United been a lil' better in 1st half and we would have clinched a draw; maybe even a win.
The duel between United and Tottennham has always been an interesting one as they are the 2 top teams in EPL who still uses 4-4-2 and rapid-firing wingers. United has been coming on top over the years; given a better ammunition on the wings despite the good squad at Spurs. But given that Valencia and Young were out and Nani/Giggs were terrible, Bale & Lennon shined today and this might have proved the difference. Add to that, a very good Walker, excellent Vertonghen, a vastly more beastly midfield in Sandro/Dembele and a disciplined squad and it's why Spurs thumped United in all compartments in the first half.