A keenly-contested game unravelled for us in a ten-minute spell in the second half when Albion scored all the goals and we had a man sent-off.
It was clear from the start that both sides wanted to play. Boro pressed from the off, Brighton, unbeaten in 15 90-minute games (losing on penalties in a cup game), keen to knock the ball around and use the full dimensions of the pitch.
The fans in the Amex had to wait until the 11th minute before the first effort on goal from either side, Kian Spence hitting a well-struck effort straight at goalkeeper Robert Sanchez.
A deep cross from Aleš Mateju threatened briefly, until intervention from Robbie Tinkler afforded the Seagulls nothing more than a corner.
Determination from Hayden Coulson in the Brighton box set up Connor Malley on the edge of it and a low shot brought a full-length save from Sanchez. From the resultant corner Luke Armstrong headed wide.
A few minutes later Armstrong mis-hit over the bar from close range when set up by Tyrone O’Neill.
In each of their previous three games Brighton had scored five goals, but in the opening 45 there was little sign of that potency, although it took sterling work from Tinkler to keep out a low effort from Henrik Bjordal.
Smart work from Zach Hemming (twice) helped repel a brief flurry from Simon Rusk’s side shorty before half-time, but that was the closest the home team had come.
Brighton wasted two good chances as the game approached the hour mark as first Daniel Mandroiu mis-kicked in the box, then Mateju shot well over from just a few yards away.
Not long after, Hemming produced a full-length save away to his right to tip around a low shot from Steven Alzate.
Then it was out turn to squander a good chance, but O’Neill shot over when well placed inside the box, before Malley just cleared the bar from the edge of the box.
Hemming was soon back in action, well positioned to deal with a Viktor Gyokeres header and soon after Mandroiu volleyed inches wide as the game opened up.
The opening goal game on 70 minutes when Viktor Gyokeres wasn’t picked up inside the box and powerfully headed home across Hemming – Gyokeres was scoring for the seventh game in succession.
Our task was made harder with 75 minutes played when Tom Brewitt was shown a straight red for a tackle.
Albion capitalised, cut loose and won the tie with two more goals in three minutes.
With 77 minutes played Henrik Bjordal took advantage of a loose ball inside the box to crack home from close range, then Viktor Gyokeres rammed home the advantage when scoring his 11th of the season as we were cut open through the middle.
It was enough to send Albion to the Play-Off finals where they will meet the winner of the other semi-final between Aston Villa and Reading.
Scorers Gyokeres 70, Bjordal, Gyokeres, 80
Brighton Sanchez; Mateju, Cox (Cochrane 84), Hünemeier, Dallison, Sanders (Capt.), Bjordal, Alzate, Connolly, Mandroiu (Hutchinson 89), Gyokeres (Tilley 82). Subs Collings, Barclay.
Boro Hemming; Tinkler, Mahmutovic, Brewitt (Capt.), Reading, Malley, Spence, Liddle, Coulson, O’Neill (Curry 71), Armstrong (Walker 86). Subs James (gk); Hegarty, Dale.
Referee David Rock
Boro Mahmutovic 80, attempted foul
Boro Brewitt 75, straight red for a foul
Conditions Mild and wet