Tottenham Hotspur needed a 73rd-minute Andros Townsend penalty to end the dogged resistance of visiting third tier Sheffield United and secure a 1-0 lead in their League Cup semi-final first leg on Wednesday.
It had looked like being a frustrating evening for the Premier League side and four times winners, whose laboured efforts to break down their lower league opponents came to nothing for most of the encounter.
Yet a blatant handball by United's Jay McEveley gave the hosts the chance to finally break the deadlock and Townsend walloped home from the spot to give them a slender advantage heading into next week's second leg at Bramall Lane.
"In the first half it was very difficult to create chances because they played very deep and were well organised. In the second half our performance improved and we did create some chances," Spurs manager Mauricio Pochettino told reporters.
United boss Nivel Clough added: "We're disappointed not to come away with a draw tonight. We let it slip a little bit in the second half when we didn't play enough leading up to the penalty. But we are still in the tie."
The winners face either Liverpool or Chelsea, who drew 1-1 in their first leg on Tuesday, in the final at Wembley.
The League One side have become cup specialists under manager Nigel Clough, having lost two of their previous 19 knockout games and beaten five Premier League sides in the last 12 months.
While the kickoff was delayed 15 minutes after the visitors' bus got stuck in traffic, there was nothing tardy about their start to the game.
They looked to give as good as they got in the opening exchanges, although the first real chance fell to Spurs, with defender Eric Dier having a header well parried by visiting keeper Mark Howard.
Spurs, bidding to reach their first final for six years, enjoyed the lion's share of possession but struggled to break down a plucky United rearguard.
Tottenham's Togo striker Emmanuel Adebayor, making his first start since November, blasted over 10 minutes before halftime, typifying a sloppy first 45 minutes from the home side.
As the frustration levels increased inside White Hart Lane, so did the visitors' resilience, as Tottenham laboured for little attacking reward.
Spurs boss Pochettino replaced the ineffective Adebayor with Roberto Soldado midway through the second half and the Spaniard had a hand in the breakthrough moment.
He controlled a crossfield pass into the box from central defender Jan Vertonghen and McEveley's trailing arm fumbled at the bouncing ball in front of referee Neil Swarbrick who had no hesitation in pointing to the spot.
