On a dramatic and tense night in South Yorkshire, the Danish playmaker scored a sublime 25-yard free-kick to open the scoring, before the home side hit back with a quick-fire double late in the game which looked to be sending the contest into extra time.
But, with the aggregate scores locked at 2-2, Eriksen produced a cool, composed finish with just two minutes remaining, sliding the ball into United’s net to break Blades’ hearts and edge us into the final.
The game kicked off in a snow flurry and with both sets of fans in fine voice, but we made a bright start, controlling possession and taking any sting out of the contest in the opening stages.
And on three minutes we had our first sight of goal when Harry Kane nicked the ball off Jay McEveley down the right channel and skipped into the box. His low cross was whacked clear and from the throw-in, Erik Lamela beat two defenders but his attempted curling effort was high and wide.
The Blades had a golden opportunity to level the tie on aggregate on 10 minutes, only to be denied by their former player Kyle Walker. Jamal Campbell-Ryce’s cross was spilled by Michel Vorm, the ball fell to Jamie Murphy eight yards out but his drive was blocked on the line by the ex-United man and we survived.
In truth, that was as good as it got for the home side in the first period as we dominated from then on. Eriksen and Lamela combined well in midfield on 13 minutes, Lamela’s neat pass found Kane who cut inside and hit a left foot drive but it was straight at Mark Howard.
The excellent Mousa Dembele dragged a 25-yard shot wide after a patient build-up, Lamela led a swift breakaway and released Kane who drilled wide from the right edge of the area and Ryan Mason hit a speculative shot from fully 40 yards out which Howard had to parry away and gather at the second attempt.
The opening goal on the night came just before the half-hour mark and what a goal it was. Benji Stambouli was upended 25 yards out to the right of goal, Eriksen stepped up and hit a stunning right-foot effort up and over the wall and right into the top corner of the Blades' goal, a superb strike.
It was no more than we deserved as we continued to control proceedings, going close again on 33 minutes when Howard saved with his feet from Kane’s close range drive, while some magnificent trickery from Dembele saw him weave his way to the byline and cut back for Mason, but he fired well wide from the edge of the area.
We always had to be wary of the Blades though and they went close again on 43 minutes when Stefan Scougall broke away down the right and squared a ball for Marc McNulty, but his right-foot shot from distance was a yard wide of Vorm’s far post and we went in ahead on the night and 2-0 up on aggregate.
We were immediately on the offensive when play resumed after the interval, Dembele driving through the heart of the Blades defence before finding Kane on the left, but he dragged his shot wide.
On 53 minutes, Murphy cut in from the left and hit a 25-yard shot which was off target, while at the other end Kane bustled his way through into the area and tested Howard, who was again equal to his effort.
A free-kick out wide for United saw Murphy shape to cross but instead he laid the ball back to the edge of the area where Jose Baxter was on hand to hit a fierce drive goalwards which was blocked as the home side stepped up the pace of their game, in search of the goals they needed to stay in the tie.
We were awarded another free-kick on 67 minutes, Kane stepping up this time but Howard saved comfortably, and moments later a swift counter saw Lamela breaking into United’s half and threading a pass to Mason, who got a toe to the ball ahead of Howard but poked it just wide.
Just when the game had started to enter a bit of a lull, the Blades set the stadium alight with a goal to put them right back in the contest. Ryan Flynn sent over a cross to the far post where substitute Che Adams was waiting and he fired past Vorm.
And with their tails up, the home side added a second to level the tie on aggregate just two minutes later and it was that man Adams again, on hand to smash a shot into the back of the net, his effort taking a deflection on its way in.
Suddenly the game was alive again and in the balance and Louis Reed had a great chance for Nigel Clough’s side on 84 minutes, collecting a pass inside the area but firing over the bar. At the other end, Mason just couldn’t take Ben Davies’ pass under his control and it ran through to Howard.
And then the game turned once more... this time in our favour. With just two minutes remaining, Kane received the ball inside the United half and turned goalwards before threading a delightful pass in to Eriksen racing through the middle. As Howard came out, he produced a deft finish to slip the ball into the bottom corner and put us back in front on aggregate, celebrating with his team-mates in front of the delirious Spurs fans.
As the clocked ticked down, Chris Basham suddenly found himself through on goal at the other end, but Vorm was quick off his line to dive bravely at his feet, getting injured in the process although he was soon up and able to carry on.
There were no more scares in the closing seconds and referee Mike Dean’s final whistle was greeted with a mixture of delight and relief by anyone of a Spurs persuasion... but most importantly, it signalled our return to Wembley Stadium. Roll on March 1!
United: Howard, Flynn, McEveley, Basham, Harris, Doyle (Reed 65), Campbell-Ryce (Adams 73), Scougall, Murphy, McNulty (Higdon 73), Baxter. Substitutes (not used): Turner, Alcock, Kennedy, Wallace.
Spurs: Vorm, Walker, Vertonghen, Dier, Davies, Stambouli, Mason (Rose 90), Lamela (Townsend 73), Dembele (Paulinho 65), Eriksen, Kane. Substitutes (not used): Friedel, Fazio, Soldado, Adebayor.
Goals: United – Adams 77, 79; Spurs – Eriksen 28, 88.
Yellows: United – Doyle, Flynn; Spurs – Walker, Mason, Dembele.
Referee: Mike Dean.