United soaked up a lot of pressure in the first half before hitting Spurs on the break to go in front and eventually win at a canter.
Ferguson said: “We carried a bit of luck. It’s an entirely unbelievable result. I would say that’s our hardest away game of the season.
“In fairness, the first half, we were never at the races. Maybe we got our tactics wrong. What we tried to do was come back off them and sit back a little bit and draw them onto us and then play on the counter-attack. But it didn’t work.”
