Shelbourne manager Joey O'Brien implored his players not to fall prey to tension as they seek to secure league phase football in Europe for the first time.
The 2024 Premier Division champions head to Windsor Park for the second time this summer, holding a 3-1 advantage from the first leg after last week's occasionally nervy win in Drumcondra.
Leading 2-0 early in the second half and playing against 10 men following Matthew Fitzpatrick's first half second off, Shels almost let things slip, Kieran Offord pulling a goal back after 53 minutes.
Moments later, David Healy's side had a chance to level it after Paddy Barrett handled the ball at the back post under pressure from Sam Roscoe. Wessel Speel's penalty save preserved their lead and Evan Caffrey subsequently doubled their advantage in a dominant final quarter.
O'Brien is anxious that Shels learn the lessons of the second-half wobble in the opening leg, reminding his charges not to get "too safe".
"You saw how tight the game was last week. The difference between 2-2 and 3-1 was a penalty save," O'Brien said in an interview on Shelbourne's YouTube channel.
"It's all about getting a fast start ourselves. Attacking the game early and getting on the front foot.
"We have a small advantage going into it. But that mentality of just sitting back and thinking we're OK... that was a lesson learnt from last week.
"I think at 2-0 the lads probably felt on the pitch they were a little bit safe. But when you're safe, you're unsafe. Within the space of five or ten minutes, they've a big opportunity to turn it into a 2-2 and it's a different game completely. That was the big takeaway last week for our lads.
"It's about both teams going out and going after that first goal. That first goal has a big say in the overall tie."
Provided they can avoid a two-goal defeat, Shelbourne will progress to the league phase of a European competition for the first time, 21 years after they famously got to within one round of reaching the Champions League group phase.
While Conference League qualification wouldn't be on a par with it, the achievement would be a major boon for the club, financially and otherwise, and guarantee a lengthy European odyssey for the remainder of 2025.
"It's been great (the European run). From the club point of view, from the players point of view, from the fans point of view, you want that to continue.
"You're greedy. But here, it's not just about talking about it. You have to go out and perform.
"It's a massive, massive game. It probably defines this last couple of months. But as I keep saying, that can't be a tension. That has to be a motivation. To go out and perform and enjoy it and embrace it. You want more of these moments because this is what it's all about."
Half-time: Shelbourne 1-0 Linfield
— RTÉ Sport (@RTEsport) August 21, 2025
A second penalty in four minutes for the hosts and Harry Wood converts this one
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Six weeks ago, Shels came to Belfast and booked their progression to the next phase of the Champions League with a 1-1 draw following a composed performance.
Since then, the Irish League champions have had wins over Zalgiris of Lithuania and Faroese outfit Vikingur and were highly competitive in Tolka Park, despite the 3-1 reversal.
Shelbourne midfielder Harry Wood, who slotted the penalty just before half-time last Thursday, stresses that they have to be wary of the hosts.
"If we can score three (at home), then they can score three. We know they're a good team, a top side. Been at this level for a long time, longer than us.
"We have to take them seriously like we have for the last three (games) and bring our A-game."
Linfield boss Healy (pictured above) certainly hasn't given up hope.
"It's a tough ask but it's one that we still feel that we're capable of coming out the other end with a positive result," he told the BBC.
"We've been there three times, we understand the way they're going to play. Fine margins probably cost us last week in terms of the way the game went.
"Obviously being down to 10 men after 17, 18 minutes certainly didn't help us, but great credit to the players, they showed a little bit of resolve… and there were opportunities. We missed a penalty, you always felt as if we were capable of scoring.
"So with 11, an excitable crowd, a little bit of electricity in the atmosphere, hopefully we're a little bit more clinical."
Linfield were fined €10,000 and handed a suspended partial stadium ban for the "racist and/or discriminatory behaviour of its supporters" and fined €2,000 for the the lighting of fireworks in the July visit of Shelbourne for a Champions League qualifier.
Healy hopes the club's fans can play "a huge role, in a positive way" tonight and warned: "Don't be letting the club down.
"We have an unbelievable fan base, especially here on a European night. This place can be electric, so we're asking them to come in early, get behind the team and create the atmosphere.
"And then when we start the game, get behind the players and try and help us get the first goal.
"Getting the first goal is paramount. If we get it, then who knows what can happen after that."
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