Stevenage and Sheffield United played out a goalless draw in their League One play-off semi-final first leg.
Craig Reid struck the United woodwork, while Boro goalkeeper Chris Day had to tip over a header from his own midfielder Michael Bostwick.
John Ashton failed to scramble in a Stevenage corner, while Kevin McDonald's deflected shot almost deceived Day.
But neither side could find a goal ahead of Monday's second leg.
Stevenage and the Steel City
Stevenage have not lost to either Sheffield side this season, doing the double over Wednesday and taking two draws and a victory from their three encounters with United.
The game brought together two clubs possessing contrasting recent histories, with Stevenage looking for their third promotion in as many seasons and United - a Premier League outfit as recently as 2007 - seeking an instant return to the Championship.
Boro, who had been restricted to long-range efforts throughout the first half, came within inches of taking the lead when Steve Simonsen finger-tipped Reid's 25-yard dipping shot against the bar.
It came minutes before the break but seemed to draw United out of their shells for the closing stages of the first period.
A back-pedalling Day was forced to touch team-mate Bostwick's wayward header over the bar and Stephen Quinn dragged a grass-cutter wide of the post.
Continuing in that vain after the break, the visitors' Lee Williamson, who had a penalty claim dismissed following a challenge from Luke Freeman, drove straight at Day when cutting into the area.
But Stevenage, who showed they have the mettle for play-off showdowns last season when they were promoted from League Two, were able to rally, causing problems with Freeman's desire to run at defenders and, most notably, when Ashton should have done better when attempting to convert from four yards out.
The Blades, who have never tasted play-off success, almost stole something when McDonald's deflected effort spun its way into the arms of the wrong-footed Day.
And, despite an open and frantic final 10 minutes, Stevenage held out to record their 21st clean sheet of the campaign.
Stevenage manager Gary Smith:
"Sheffield came with a game plan and a good game plan, which was to frustrate some of our fluent play they may have seen in previous matches.
"Ultimately we're disappointed to have not made clear cut chances and not made the most of one or two openings.
"It's come to something when we say a draw against Sheffield United is disappointing.
"The pressure is on them to make something happen. We scored twice there two weeks ago so there's no fear from us."
Sheffield United manager Danny Wilson:
"It's finely balanced and we're taking nothing for granted.
"We have to have the same determination we had today. If we get carried away the second leg will go against us.
"We've seen too many times where people make assumptions after the first leg result - they think it's a foregone conclusion and it's far from that."
Full Time The referee blows for the end of the match.
Corner from right by-line taken by Lee Williamson. Lee Williamson takes a shot. Blocked by Scott Laird.
The ball is sent over by Jennison Myrie-Williams, Harry Maguire gets a block in.
Substitution Richard Cresswell on for Ryan Flynn.
Substitution Johnny Ertl on for Kevin McDonald.
Luke Freeman concedes a free kick for a foul on Lee Williamson. Harry Maguire restarts play with the free kick.
The offside flag is raised against Patrick Agyemang. Steve Simonsen takes the indirect free kick.
Unfair challenge on John Mousinho by Kevin McDonald results in a free kick. Scott Laird takes the free kick.
Substitution Jennison Myrie-Williams joins the action as a substitute, replacing Jamaal Lascelles.
Free kick awarded for an unfair challenge on Ryan Flynn by Jamaal Lascelles. Free kick taken by Stephen Quinn.
Michael Bostwick has a drilled shot and missed to the right of the net.
Kevin McDonald takes a shot. Save made by Chris Day.
Corner from right by-line taken by Luke Freeman.
Substitution (Stevenage) makes a substitution, with Robin Shroot coming on for Joel Byrom.
The ball is sent over by John Mousinho.
Substitution John Mousinho is brought on as a substitute for Craig Reid.
Short corner taken by Lee Williamson from the left by-line. Lee Williamson takes a shot. Save by Chris Day.
Corner taken by Lee Williamson from the left by-line, Shot from 12 yards by Stephen Quinn. Jon Ashton gets a block in.
Chris Porter fouled by Mark Roberts, the ref awards a free kick. The free kick is delivered left-footed by Stephen Quinn from left channel.
Unfair challenge on Lee Williamson by Joel Byrom results in a free kick. Matthew Lowton restarts play with the free kick.
The referee blows his whistle to start the second half.
45:00 +1:33 Half time
Half Time It is the end of the first-half.
Corner taken right-footed by Lee Williamson from the right by-line, Mark Roberts manages to make a clearance. Kevin McDonald produces a right-footed shot from just outside the box that goes wide left of the goal.
Stephen Quinn produces a left-footed shot from just outside the area that goes harmlessly over the bar.
Craig Reid takes a shot.
Free kick awarded for an unfair challenge on Scott Laird by Lee Williamson. The free kick is delivered left-footed by Joel Byrom from left wing, clearance made by Matthew Lowton. Luke Freeman takes a shot. Neill Collins gets a block in.
Luke Freeman takes a shot. Neill Collins gets a block in.
Chris Porter gives away a free kick for an unfair challenge on Scott Laird. Direct free kick taken by Chris Day.
The ball is crossed by Luke Freeman, Neill Collins makes a clearance. Unfair challenge on Chris Porter by Jon Ashton results in a free kick. Lee Williamson restarts play with the free kick. Michael Doyle takes a shot. Blocked by Craig Reid.
Shot from just outside the area by Luke Freeman goes over the bar.
Ryan Flynn challenges Lawrie Wilson unfairly and gives away a free kick. The free kick is delivered left-footed by Joel Byrom from right wing.
Free kick awarded for a foul by Michael Bostwick on Matthew Hill. Neill Collins takes the free kick.
Shot from just outside the area by Michael Bostwick goes over the bar.
Mark Roberts fouled by Kevin McDonald, the ref awards a free kick. Free kick taken by Joel Byrom.
Free kick awarded for a foul by Michael Bostwick on Lee Williamson. Matthew Lowton takes the direct free kick.
Joel Byrom takes the inswinging corner, clearance made by Chris Porter.
Corner from the right by-line taken by Joel Byrom, clearance made by Neill Collins.
Corner taken by Lee Williamson played to the near post, clearance made by Mark Roberts. Lee Williamson takes a short corner.
Luke Freeman produces a cross.
Patrick Agyemang gives away a free kick for an unfair challenge on Harry Maguire. Direct free kick taken by Steve Simonsen.
Matthew Lowton challenges Luke Freeman unfairly and gives away a free kick. Joel Byrom crosses the ball from the free kick left-footed from left wing.
Matthew Hill fouled by Patrick Agyemang, the ref awards a free kick. Matthew Hill takes the direct free kick.
Shot from just outside the box by Scott Laird goes over the bar.
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