Relief the prevailing emotion as Middlesbrough return to top flight

If you'd like a succinct definition of optimism in nine words, it flashed up on the scoreboard of the Riverside at about 2.15pm on Saturday. 'Please keep off the pitch at the final whistle' read the message, imploring the Middlesbrough fans to remain in the stands after the end of their unbearably tense, promotion-deciding encounter with Brighton. After the 1-1 draw that confirmed their place in the Premier League next season, one of Donald Trump's walls couldn't have prevented a big slice of the 33,806 present from flooding onto the turf.

This wasn't a textbook performance from Boro, or really one that suggested Premier League quality. But in the end it didn't really matter how they got there – Middlesbrough are a top flight club again, this point ensuring they finished second on goal difference, ahead of Brighton and behind champions Burnley. The relief was twofold: firstly of course securing a place in the elite, but also avoiding the absolute head-crushing horror of the play-offs. They froze in the final last season, but now they can kick back and watch everyone else flail in terror.

The last time Middlesbrough needed a result on the final day of the season to earn promotion, it was a comparatively breezy affair: a brace of braces from Craig Hignett and Alun Armstrong gave them a 4-1 win over Oxford in 1998. This time it wouldn't be so easy, and tension was the inevitable theme of the afternoon.

On the way to and around the ground before the game, there seemed to be a sense of optimism and boisterousness from the Brighton fans, while the home crowd appeared rather more cagey and nervous. That could reflect the respective expectations of the two sides - Boro were constructed for promotion from the start of the season, but for Brighton it was very much an unexpected bonus – or it could be that they just had a little extra time to 'loosen up' on the journey from the south coast.

That said, the roar from the Boro fans when the players emerged to warm-up, with the Riverside still only a third full, was louder than for goals at a good few Premier League grounds. And it got louder throughout the warm-ups: things like handing out flags and scarves to fans, as they did here, can feel gimmicky, but there's a reason clubs do it. The ground was full 15 minutes before kick-off, and were it not for the players doing shuttle runs and passing exercises, from the noise you'd think it was midway through the first half. It felt like half encouragement, half a venting of nerves via vocal cords.

However, if off the pitch Boro seemed the nervous ones, on it Brighton looked terrified. In previous weeks their football has been rapid, attacking and threatening, but in the first half they looked tired and confused, as if the 12.30 kick-off had played havoc with their circadian rhythms. Boro should probably have been three or four ahead before the break just from chances presented to them by the visitors. Gordon Greer, drafted in at centre-back, hadn't played a league game since February: it looked as if he'd been away for much longer. It was an edgy affair all round, not one that most would actively enjoy, and in that respect the perfect man was in charge: referee Mike Dean tends to suck the life out of any game he officiates, and early on he held up the taking of a throw to ensure that three balloons that had strayed onto the pitch were destroyed. A textbook Dean moment.

Christian Stuani gave Boro the lead in the first half, but even as they led the tension built as they failed to take full advantage of Brighton's uncharacteristic incompetence. The Seagulls surely could not be so bad in the second half, and so it proved, Chris Hughton shoving them out of the dressing room and back onto the pitch early after the break, the tell-tale sign of a manager disgusted with his charges. Dale Stephens looped a header into the net to equalise, but four minutes later he was trudging down the tunnel, having been sent off for gouging a hole in Gaston Ramirez's shin with his studs. In truth it wasn't a challenge with any great malice, but a high and foolish one, and referee Mike Dean appeared to react to the injury, blood pouring from Ramirez's leg. After the game Hughton said the referee initially pulled out a yellow card, only for him to be persuaded to increase the punishment by his assistants. Dean wouldn't be the first official to be shocked into a decision by some on-pitch gore.

In the last 20 minutes, after Brighton had equalised, Boro looked thoroughly confused: with a man advantage and knowing a draw would be enough to secure promotion, their attacks were uncertain and tentative, not sure whether to kill the game off or hang on, carrying the air of a team who daren't go forwards with too much conviction lest they concede. “It was a typical Championship game,” said Karanka later. “A typical Middlesbrough game.”

He wasn't quite right. If Championship games were all this tense then cardiac wards up and down the country would have to triple in capacity. To give you an idea of just how tightly wound everyone was in the closing stages, the usually mild-mannered Hughton, famously one of the nicest men in football, squared up to a member of the Boro coaching staff in a disagreement over a throw-in. It was that sort of game, and eight minutes of added time, necessary after Ramirez's injury, didn't help calm things down at all.

But then it was over, the PA announcer impotently repeated the requests for the fans to stay off the pitch, obviously to no avail, and very quickly the grass was covered by red shirts and flailing limbs. Several Boro players were carried shoulder high; left-back George Friend was relieved of his shirt; a woman in a wheelchair made her way onto the pitch; another fan removed his top and slid across the turf. Pulsing relief was the prevailing emotion with the fans, and with the Boro manager too.

After the game Karanka looked like a man who had just been told a large debt had been written off, relieved to the extent that he, not a natural comedian to say the least, even cracked a couple of jokes. “I couldn't sleep for the last...I don't know how many days,” he said, repeating how tough the last couple of years – in which he lost a play-off final and was almost sacked at least once – have been, and that he had doubts whether they would actually be able to achieve promotion.

“Tomorrow, we're going to disappear,” he said, about his impending holiday plans. “I don't know where, but I need time to rest.” In the end, he's earned it.