Bright start from Preston as they launch an attack inside the first minute. Joe Garner takes an air swing from the edge of the area before the ball is fizzed back into the Chesterfield box and cleared.

We are now under way at both the Proact Stadium and Bramall Lane. Let battle commence.

At both grounds, the teams are just emerging from the tunnels to rousing receptions. It looks like the sun is shining in both Chesterfield and Sheffield too - what I like to call 'play-off weather'.

Kick-off is moments away.

While Mark Cooper has been busy trying to pile all the pressure on Sheffield United, their forward Jamie Murphy has suggested it's rather more difficult to pick a winner.

"I don't think there is a favourite," the 23-year-old told BBC Radio Sheffield. "I think any of the four teams can get through to the final and go up."

You can't beat some good, old-fashioned mind games.

Image source, Getty Images

Although Swindon have made a greater impression on League One than Sheffield United this season, finishing one place and nine points above them, Robins manager Mark Cooper still insists the Blades are "expected" to get promoted.

"The pressure on them is the expectancy," Cooper told BBC Wiltshire.

"Because it's such a big club they're expected to get promotion, whereas we're not. They've shown before they can deal with that, but let's hope they don't."

Image source, Getty Images/BBC

While the Blades have been busy enjoying themselves in the cups, Swindon Town were embroiled in a four-way tussle for the automatic promotion places from early in the season.

Their campaign included excellent wins over eventual champions Bristol City and play-off rivals Preston North End, as well as a handful of brief flirtations with top spot.

However, a surprise home defeat at home by Yeovil Town last month finally ended any hopes of finishing in the top two, and sparked a fortnight of experimenting for manager Mark Cooper.

The Robins have used a whopping 27 players since that loss to the Glovers, though you'd imagine the rotating will stop here.

Image source, Getty Images/BBC

It's been a busy old nine months for Sheffield United.

The Blades have been fighting firmly on three fronts this season, reaching the semi-finals of the League Cup, which they lost 3-2 on aggregate to Premier League side Tottenham Hotspur, and winning 3-0 at Queens Park Rangers on their way to making the fourth round of the FA Cup.

As a result, Nigel Clough's side could probably be forgiven for starting a little slowly in the league.

They have, at least, looked a pretty safe bet for the play-offs since before Christmas, though they never managed to climb higher than their finishing position of fifth.

Swindon Town defender Harry Toffolo:, external Gutted to miss the game through injury! I'm sure the boys will do the job! Come on Swindon!

How are we feeling about Harry's absence tonight, Robins fans? Will he be a big miss? Let us know by using #bbcfootball on Twitter.

Image source, Getty Images

Chesterfield boss Paul Cook has said he does not see his side as underdogs for this evening's play-off semi-final first leg with Preston.

Cook, who guided Chesterfield to the League Two title last term and then a sixth-place finish in League One, told BBC Radio Sheffield: "We'll be considered by most to be the underdogs but we don't think of it that way.

"You have to have belief in what you do and we deserved to finish where we did in the table.

"You can over-complicate what you are trying to do, but if we win two games then we will be at Wembley."

Image source, Getty Images/BBC

What a story it has been for Chesterfield this season. After winning League Two in 2013-14, their return to the second tier has had its ups and downs.

After hovering around the play-off places for much of the campaign, a slump in form saw Paul Cook's men fall to mid-table in March.

However, four wins on the bounce either side of Easter pushed the Spireites into sixth and that's where they stayed.

After bouncing between the third and fourth divisions in recent decades, can Chesterfield finally reach the second tier for the first time since 1950-51?

Image source, Empics/BBC

As a result of that loss, Preston North End will face Chesterfield in the play-off semi-finals tonight. And so now may be a good time for their fans to look away, as this next stat does not make pretty reading.

In the Lilywhites' 21 play-off games since 1989, they have won only three of those and gone out at the semi-final stage six times.

However, despite Sunday's defeat at Colchester which saw MK Dons pip them to an automatic spot, North End enjoyed a fine season in League One.

From mid-October onwards they never dropped any lower than fourth in the table, only lost seven games all season and went on that 18-game unbeaten run before the final-day loss in Essex.

Image source, Getty Images

Preston North End will need to pick themselves up tonight after Sunday's 1-0 loss at Colchester, which denied them automatic promotion.

Manager Simon Grayson admitted his side were "devastated" as their 18-game unbeaten run came to an end at the worst possible time, allowing MK Dons to snatch second place on the final day of the campaign.

"The dressing room is devastated, we're all devastated as staff and the supporters will be," the 45-year-old told BBC Radio Lancashire.

"We knew fate was still in our hands, we knew what we had to do and unfortunately we didn't play as well as we could do."

Ian Woodcock
BBC Sport at Bramall Lane

Image source, Empics

"They say Wembley is no place for losers and the two teams at Bramall Lane tonight can certainly vouch for that.

"Sheffield United's play-off record reads seven attempts, seven failures. They tasted defeat under the arch in 2012 when Yorkshire rivals Huddersfield recovered from missing their first three penalties to beat the Blades to promotion to the Championship.

"They qualified for the play-offs again the following season, but lost to Yeovil in the semi-final. No wonder boss Nigel Clough has said 'history means nothing' in his programme notes.

"If they're looking for sympathy from Swindon, they're unlikely to get it. The Robins lost 1-0 to Millwall in the League One play-off final in 2010.

"Charlie Austin, in his first season as a professional player, missed a great chance to level for the Wiltshire side when he was played clean through on goal with 20 minutes to go. The ball bobbled, the chance went begging and, just to rub salt in the wound, they were relegated the following season."

So, there's around half an hour to go until the first of this year's Football League play-off matches get under way. Do stick with us, as we'll be hearing from all four camps involved tonight between now and then.

Chesterfield: Lee, Jones, Evatt, Hird, Darikwa, Morsy (capt), Ryan, Roberts, O'Shea, Gardner, Clucas.

Substitutes: Talbot, Raglan, Banks, Ariyibi, Humphreys, Harrison, Gnanduillet.

Preston North End: Johnstone, Clarke (capt), Wright, Huntington, Laird, Humphrey, Welsh, Gallagher, Johnson, Beckford, Garner.

Substitutes: Stuckmann, Woods, Wiseman, Kilkenny, Robinson, Hugill, K. Davies.

Image source, Empics

Both teams are unchanged from their final games of the regular season which saw Chesterfield draw 1-1 at Sheffield United and Preston lose 1-0 at Colchester.

There's plenty of experience on both sides. The Spireites have Ian Evatt, who has been in this situation before, winning promotion with Blackpool.

Preston have no shortage of firepower, with Joe Garner and Jermaine Beckford up front and the evergreen Kevin Davies waiting on the bench.

Sheffield United: Howard, Harris, Brayford (capt), Basham, Flynn, Murphy, Coutts, McEveley, Freeman, Davies, Holt.

Substitutes: Alcock, Doyle, Scougall, McNulty, Done, Turner, Adams.

Swindon Town: Foderingham, Stephens, N. Thompson (capt), Turnbull, Byrne, Kasim, Luongo, Gladwin, Ricketts, Smith, Hylton.

Substitutes: C. Belford, Barthram, Marshall, Rodgers, Swift, Williams, Obika.

Image source, PA

We already knew Sheffield United would be without Louis Reed because of a heel injury, but a surprise absentee for the Blades is forward Jose Baxter, who is out through illness.

The big news emerging from the Swindon Town camp, meanwhile, is that defender Harry Toffolo has not been passed fit to play, so he misses out.

In all, Sheffield United have made six changes, while Swindon Town have made nine. More on the rotating Robins a bit later...

Tonight we'll be focusing firmly on League One, as Preston North End face a trip to Chesterfield and Sheffield United host Swindon Town at Bramall Lane.

Who do you think will follow Bristol City and MK Dons up to the Championship? And, the all-important question, do you love the play-offs or hate them?

You can tell us all that and more by using #bbcfootball on Twitter.

BBC Sport

Image source, Getty Images

Between now and Monday, 25 May, 12 teams across the Football League will see their campaigns extended by two, possibly three, more matches as they gun for promotion.

And, I'm pleased to tell you, we'll be bringing you live text commentary on every one of those games right here on the BBC Sport website.