Double, Double still alive for Gunners
Freddie Ljungberg's first half strike was enough to send Arsene Wenger's men through to their third-straight final appearance at Cardiff's Millennium Stadium.
However, they were made to work very hard by Neil Warnock's men, who were brilliantly denied with a glorious save in the final stages by England goalkeeper David Seaman.
The Blades started positively with some surges forward as the opening quarter-of-an-hour was very much an even-looking contest.
Arsenal's Sylvain Wiltord showed some threat on the counter-attack with runs down the left but Sheffield United's back-line looked solid with timely interventions of their own.
The Blades also showed some threat going forward and nearly opened their Premiership opponents up, when Michael Brown's cross from the right nearly found Wayne Allison at the far post but Lauren made a timely flick away for a corner.
The all-important breakthrough came nine minutes before the break in somewhat controversial circumstances, as Allison was down injured and referee Graham Poll inadvertently blocked Michael Tonge from making a crucial challenge in midfield.
Arsenal broke forward with Francis Jeffers getting to the by-line and his cutback in front of goal found Wiltord, whose shot hit the far post. The Frenchman did not rest as pounced on the rebound and turned the ball back towards the middle via a deflection, where Ljungberg pounced and finished to give the holders the lead.
Despite going a goal behind, Neil Warnock's men remained positive from the re-start and created an early chance to equalise but after good work from Brown to feed Peter Ndlovu, the Zimbabwean's shot went straight at Seaman.
The Gunners were then forced into an untimely substitution, as Patrick Vieira was brought off injured 11 minutes into the second period, with Brazilian Gilberto Silva replacing him.
Two minutes later, the substitute combined with fellow countryman Edu to create a flowing passing move which lead to Wiltord's low shot that Sheffield United keeper Paddy Kenny saved well.
The Blades kept pressing for that all-important equaliser and Brown was handed a chance of his own but he could only put his volley wide of goal after Sol Campbell flicked on a Sheffield United throw-in into the Arsenal box.
The crowd witnessed a fantastic finish to the match as both sides to pushed for more goals, with Arsenal coming close to a second goal when Gilberto's cross into the box found Thierry Henry, but after flicking the ball up and over his marker, he hit his shot woefully wide.
Then two minutes later, Sheffield United substitute Paul Peschisolido was brilliantly denied the opportunity of equalising when a Blades corner was knocked back in by Carl Asaba.
From a yard out, the Canadian international's header looked destined to go in but Seaman remarkably clawed the ball back out from on the goal-line, leaving Blades supporters in stunned disbelief.
The result takes Arsenal to their third final in as many years while Sheffield United must concentrate on a season-ending campaign in the Division One play-offs.
Click below for match stats:
FA Cup semi-final
Arsenal 1-0 Sheffield United
