Iliman Ndiaye was the matchwinner for the Blades, coming off the bench to score a superb solo goal to help down a Spurs side who barely got out of first gear at a rowdy Bramall Lane.
Boss Paul Heckingbottom said: "We've had a top side come here and we've put on a good performance. We've spoken about treating the league and cup separately; there's a tension and an anxiety in the league and there's been a different feel in the cup. We want to play with that freedom, but we also want to win."
Here’s how we rated United’s players as they sealed progression to the last eight of this famous old competition ...
1. RIP Motty
Sheffield United players take part in a minute's applause in memory of John Motson: Paul Thomas / Sportimage Photo: Paul Thomas
2. Wes Foderingham 7
Made his first real save early in the second half from Perisic's flicked header and his second with five minutes to go from the same Spurs man. Apart from that had remarkably little to do, so it's hard to justify a higher mark Photo: Andrew Yates
3. George Baldock 7
Made his return after almost a couple of months out with a hamstring injury and got a rendition of his name from the Kop after a bit of argy-bargy with Perisic on the Spurs left. Picked up a yellow for a late challenge on Son and departed with some valuable minutes under his belt RESTRICTIONS: EDITORIAL USE ONLY No use with unauthorised audio, video, data, fixture lists, club/league logos or "live" services. Online in-match use limited to 120 images, no video emulation. No use in betting, games or single club/league/player publications. Photo: Simon Marper
4. Chris Basham 7.5
Gained some valuable minutes ahead of stepping in for Ahmedhodzic when the Bosnian is banned and put in a typical Basham performance, lacking no heart or skill and ability either. On the rare occasions Spurs got the better of Ahmedhodzic, Basham was there to bail his pal out of bother Photo: Simon Bellis