Tomorrow, the Championship play-offs commence with Brentford v Middlesbrough.

The Bees were promoted automatically from League One last term and they, along with Wolves who finished seventh, have proved that teams can make a successful step up to the second tier, while Rotherham completed the set by ensuring Championship survival in the last week of the season.

We'll have live text and radio commentary from Griffin Park tomorrow evening. Kick-off is at 19:45 BST.

But there are still matters to attend to in League One first...

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An excellent half of football at Bramall Lane sees Sheffield United edge ahead in this two-legged tie.

Kieron Freeman's 19th-minute strike gave the Blades a deserved lead, before Ben Gladwin had his penalty at the other end saved by Mark Howard as Swindon looked to build a recovery.

We asked earlier whether you loved or hated the play-offs. Well, I think those two sets of 45 leave both of us firmly in the "love them" camp.

Image source, Empics

Well we may have been short of clear-cut chances but there was certainly no shortage of action in the first half.

Jermaine Beckford's early goal put Preston ahead and the Lilywhites were the stronger of the two sides in the opening 20 minutes.

But Chesterfield fans will feel buoyed by their team's spirit in the closing stages of the half as they ended on top.

It seems as if there's a bit of an ugly undercurrent to the game though and things boiled over on the pitch as well as in the tunnel at half-time.

Let's hope both sets of players and staff calm down at the break - but remember - this is the play-offs and there's a lot at stake.

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Plenty for Chesterfield manager Paul Cook to ponder as he sips on his half-time cuppa - his side trail Preston 1-0.

Swindon are also a goal down at Sheffield United, but have missed a great chance to equalise, with Mark Howard saving Ben Gladwin's penalty.

How will the first legs end up? Use #bbcfootball on Twitter.

Ian Woodcock
BBC Sport at Bramall Lane

"The first legs of play-off ties can often be cagey affairs but it's been anything but that here.

"The Blades will feel they should maybe have more than just the one goal to show for their endeavour in this first 45 minutes, but Mark Howard's save from Ben Gladwin's penalty could prove to be pivotal.

"The visitors look sharp on the counter-attack and winger Nathan Byrne is having a lot of joy."

Jay O'Shea launches a free-kick from all of 35 yards high over the bar for the hosts. And that's the final action of an action packed first-half.

It appears there's also some confrontation in the tunnel as the players come off.....we may hear more about that.

The half-time whistle signals that we're exactly a quarter of the way through this League One play-off semi-final.

Chesterfield are now laying siege to the Preston goal. Jay O'Shea jinks his way into the box, his shot is blocked, and follow up efforts from Dan Gardner and Gary Roberts also see bodies flying in the way.

Preston desperate to hold onto this lead.

Australia international Massimo Luongo is often considered Swindon Town's star man. Not there, he wasn't, as his shot from distance goes high into the Kop.

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There's just a sense both sets of players are meandering their way through to the break. The same can be said for the crowd too, as a bit of a hush descends across Bramall Lane.

Stuie Neale: Town have struggled. Poor pen from Gladwin unfortunately.

Joe: Are there any other teams who have missed 5 penalties this season? I doubt it.

Swindon have had 13 penalties in League One this season, and scored just eight. Will Ben Gladwin's failure from 12 yards prove pivotal in their semi-final tie?

Now a fine save from Sam Johnstone in the Preston goal as the game continues to flow from end to end.

Dan Gardner powers a shot from outside the box but Johnstone dives low to his left to palm the ball away with a strong hand.

Good chance for Preston. Jermaine Beckford knocks the ball to an on-rushing Paul Gallagher who looks like he's clean through but Jimmy Ryan races back to put the pressure on and Gallagher scuffs the shot wide.

Another big chance for the Robins! Jermaine Hylton bursts into the penalty area and closes in on Mark Howard's goal, only to lose his footing. The ball rebounds to Nathan Byrne, however, but Howard makes a smart save with his legs.

Into the last five minutes or so of this first half.

A soft one. Steven Davies kicks the ball away after the referee penalises him for bumping into Nathan Thompson, and the Sheffield United forward gets a yellow card for his troubles.

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The game has finally settled down after a frantic opening half-hour. Jermaine Beckford's goal remains the only clear-cut chance of the game, but there have been plenty of last-ditch tackles and hefty challenges flying in.

We will do well to end the first half without a booking.

This has been a really good watch, it must be said. It's now Swindon's turn to pile forward, giving Jermaine Hylton half a sight at goal, but his shot is high and not particularly handsome.

It's end to end at the moment. Firstly Jermaine Beckford's weak overhead kick is saved easily by Tommy Lee and then Jimmy Ryan fires a shot over the bar for Chesterfield.

This is becoming an evening of penalties - given, not given and saved.

This time Jamie Murphy goes over inside the Swindon penalty area, but again the referee waves away the appeals.

That's not the tidiest of challenges from Blades defender Bob Harris, who trips Nathan Byrne inside the Robins' half. First yellow card of the evening.