Nottingham Forest boss Nuno Espirito Santo fumed "why always us?" as he felt Brighton should've had Jakub Moder sent off in Forest's 1-0 defeat on Sunday.
The winning goal came in scrappy fashion after 29 minutes when Forest goalkeeper Matz Sels flapped at a Pascal Gross set-piece and the ball bounced in off defender Andrew Omobamidele.
Brighton were far from their fluid best, perhaps suffering a hangover from their 4-0 defeat to Roma, but Forest couldn't capitalise with Divock Origi offering up two great one-on-one chances.
Forest, who dominated the second half, felt aggrieved that Brighton midfielder Moder avoided a 67th-minute red card for a lunging challenge on Neco Williams that only drew a yellow card.
"Once again it's a mistake - it's a clear red card," Forest boss Nuno told Sky Sports.
"When a manager loses a game they come in and say excuses, we lost the game and are in trouble. I have a situation to solve. We played a good game, fighting, working and should've got something from the game. Apart from the goal they didn't create too many situations. We had chances.
"Everything changes because of that decision and it's the consequence of week after week of frustration and disappointment. You tell the players to keep on going but they keep giving us these situations, it's week after week. As a club they are costing us. Please someone tell me how that's not a red card. See the image.
"I haven't spoken with Mark [Clattenberg], I've only seen the images. It's so clear. We'll send a letter, they'll apologise. We treat them well and ask them why is it happening. How many? It's week after week. Last week it cost us a point. Against Newcastle we are ahead and we should've had a penalty. All these situations, it's enough. I'm just trying to be honest.
"Just tell me why, why always us?"
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The result lifts Brighton into eighth place, five points off Manchester United in sixth. Meanwhile, Forest remain looking over their shoulder, just three points above Luton in the relegation zone.
How showed Brighton grit to get job done...
Roberto De Zerbi had been openly critical of Brighton's failure to cope with the added European demands this season but his team came out unified and committed.
Chances fell to Moder and Ansu Fati in the early stages, both supplied by Gross, before they edged ahead in the 29th minute.
Another beauty of a Gross inswinging free-kick from the left caused indecision inside Forest's six-yard box and, with Sels under pressure from Moder, Omobamidele nodded into his own net at the near post. It was a messy goal that would have infuriated Nuno Espirito Santo.
Forest should have levelled moment later when Morgan Gibbs-White's perfectly weighted pass sent Origi through on goal but his low effort was repelled by the legs of Bart Verbruggen.
Origi scampered through again just after the break but lashed wildly over from a tight angle, before Murillo thumped a free-kick straight at Verbruggen.
Brighton yet again looked to feeling the effects from their European trip as they sank deeper with Moder's tired lunge on Williams' ankle lucky not to result in a red card.
Chris Wood then forced a fine fingertip save from Verbruggen as Forest played with a front four following the introductions of Anthony Elanga, Callum Hudson-Odoi and Taiwo Awoniyi.
But despite the wealth of attacking talent on the pitch, Forest offered little in the closing stages. An ugly win for Brighton but an important one.
De Zerbi pleased with Brighton reaction
Brighton boss Roberto De Zerbi said: "I'm very happy for the reaction.
"But I had not any doubt on the human qualities of my players. We played a good game, especially in the first 35 minutes.
"After our goal, we suffered more but we didn't concede too many shots. And now we have to prepare the game with Roma. We have to play a serious game and then we will see."
What's next?
Brighton host Roma in the second leg of their Europa League last-16 tie on Thursday March 14. They head to Liverpool in the Premier League after the international break on Sunday March 31, live on Sky Sports. Kick-off 2pm.
Nottingham Forest head to Luton in the Premier League on Saturday March 16. Kick-off 3pm.
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