Boro knocked out Manchester United at Old Trafford inside the fourth round and the Championship facet had been worth winners to sentence Spurs to another trophyless season.
Not on account that a League Cup win in 2008 have Tottenham lifted a trophy and some other hugely disappointing defeat poses in addition questions over the destiny of manager Antonio Conte.
The Italian most effective took fee in November, but has already hinted he should walk away after a run of 4 defeats inside the beyond six Premier League video games.
Teenager Josh Coburn came off the bench to attain the simplest purpose with a thumping end across Hugo Lloris in the 107th minute.
Chris Wilder's men may not were pressured to play the more half-hour had Matt Crooks connected with a unfastened header from a nook.
Harry Kane did have the ball within the net for Tottenham only to be flagged offside.
But the England captain may also be once more thinking about his future as he waits to win the first foremost honour of his career.
Middlesbrough had been with the aid of a ways the brighter facet in greater time and got their reward while Coburn rifled across Lloris from Crooks' thru ball.
Earlier, Oleksandr Zinchenko captained City as classy finishes from Riyad Mahrez and Jack Grealish sent the English champions through.
