David McGoldrick's first-half winner at Swansea City fired Nottingham Forest to third in the Championship table.
The Forest striker's sweet 35th-minute volley from Chris Cohen's header clipped Swans defender Ashley Williams to deceive keeper Dorus de Vries.
Williams and Cedric van der Gun missed great openings and Swansea paid the ultimate price for missing chances.
Forest extended their unbeaten league run to 13 games as they moved two points behind second-placed West Brom.
Billy Davies' visitors showed a clinical edge when they needed it most to show why Forest are still unbeaten on the road this season.
It was the kind of gritty away win when not at full-throttle that can ensure end-of-season achievement as Forest secured their first triumph at Swansea since 1983.
And Swansea boast one of the best home records in the division and are a side that have kept 11 clean sheets, which highlights how big a win this was for Forest.
Van der Gun almost gave Paulo Sousa's men an early lead but, cutting in from the left, the flying Dutchman's angled shot flew just past the post.
He then hit the crossbar midway through the first-half as his left-wing cross deflected onto the woodwork.
Ashley Williams should have turned the rebound into the net as it dropped off the bar but the unmarked Wales defender, at the back post, headed over when it seemed easier to score.
Van der Gunn was proving to be the home side's main threat and the 30-year-old should have scored his second Swans since his summer move when Craig Beattie put him through one-on-one.
He looked set to give Swansea the lead after a neat one-two with targetman Beattie but after a good diagonal run into the box, Van der Gun could not beat Forest keeper Lee Camp, who made an excellent spieling save.
And the Swans were punished for squandering their opportunities as Forest took the lead against the run of play in the 35th minute.
McGoldrick's right-foot 15-yard volley from Cohen's headed set-up was deflected past Swans goalie de Vries by Williams and into the corner of the net.
The Forest striker's third goal of the season was one of few clear-cut chances in a tight game between two Championship play-off contenders.
Forest frustrated Swansea but Sousa's men were often guilty of not committing enough men forward for a team trailing at home - even when Sousa threw on forwards David Cotterill and on-form Lee Trundle.
Club top-scorer Trundle had scored three in two successive cameo appearances and the super sub almost did it again in the final ten minutes as he cut inside but his shot was just over.
While Forest were not a constant goal threat at the Liberty Stadium, with McGoldrick's goal a rare opening, they kept a dangerous team like Swansea at arm's length in a competent and composed manner that will make the division sit up and take notice.
Davies praises Forest work-rate
Nottingham Forest manager Billy Davies said:
"We're disciplined within this unit and I have got nothing but praise for the players.
"I am very pleased with the win as we knew we were coming up against a very good side.
"We decided to give them the ball and let them play with it in areas that wouldn't hurt us. We had a game plan but were never able to kill them off after we went ahead.
"We were made to work hard but were disciplined and looked for the counter-attacks but we missed several clear-cut opportunities.
"The spirit in the camp is good and experience has told me not to look at league positions at this stage of the season. All we can do is enjoy the moment and prepare well for the next game.
"A big thank you to the fans who made the long journey."
Sousa upbeat despite Swans loss
Swansea City manager Paulo Sousa:
"I don't think it was a fair result.
"Against good quality teams you have to take your chances and although we started the game very well, we missed a number of goal-scoring opportunities.
"We made a lot of effort against a well-organised team who came here to play defensively and look for counter-attacks.
"They wasted a lot of time during the game and I am disappointed for the fans but we were unable to give them the win we deserved.
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