Pablo Hernandez's 57th minute strike was enough to extend the gap from third-placed Fulham to five points after Scott Parker's men were held at Derby on Friday.
Championship leaders West Brom further enhanced their promotion credentials with an emphatic 3-0 win at Bristol City.
Sheffield United loanee Callum Robinson and Hal Robson-Kanu gave the visitors a 2-0 half-time lead, before the latter completed his brace late on.
The Baggies had to play the remaining 13 minutes with 10 men as influential midfielder Romaine Sawyers was shown a straight red card for an off-the-ball incident.
Meanwhile, Preston moved into the play-off places with a 2-1 win over struggling Hull.
The Tigers took a shock lead through Mallik Wilks five minutes before half-time.
But Preston came out firing after the break and scored two goals in a four-minute spell thanks to Paul Gallagher and Alan Browne.
Hull have failed to win a league game since New Year's Day and risk being sucked into the relegation battle.
Elsewhere, there were big results for four-relegation threatened clubs.
Charlton beat drop rivals Luton 3-1 thanks to a Lyle Taylor brace and a George Lapslie strike.
Luton, who had won their last two league games to reignite their survival hopes, equalised through Harry Cornick in the 36th minute, but failed to trouble the Addicks in the second-half.
The result sees the Hatters drop to the bottom of the table following wins from Wigan and Barnsley against Millwall and Middlesbrough, respectively.
Stoke also boosted their survival chances with a 2-0 victory over promotion hopefuls Cardiff.
The Welsh club missed star man Lee Tomlin, who is sidelined with what is believed to be a serious knee injury, as a Callum Paterson own goal and Joe Allen strike saw the Potters pick up a third home win in four games.
In arguably the game of the day, Scott Hogan's 91st-minute volley earned Birmingham a dramatic 3-3 draw against Sheffield Wednesday.
Jacob Murphy's own goal gave the Blues an early lead, before Barry Bannan levelled the score on 20 minutes.
Lukas Jutkiewicz restored Birmingham's advantage in the 30th minute, which lasted for just four minutes thanks to a Fernando Forestieri penalty.
Murphy atoned for his own goal by giving his side the lead for the first time in the game, however, Hogan extended Sheffield Wednesday's winless league run to seven games.
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Results
Barnsley 1-0 Middlesbrough
Birmingham 3-3 Sheffield Wednesday
Bristol City 0-3 West Brom
Charlton 3-1 Luton
Leeds 1-0 Reading
Nottingham Forest 0-0 QPR
Preston 2-1 Hull
Stoke 2-0 Cardiff
Swansea 3-1 Huddersfield
Wigan 1-0 Millwall
Leeds secured back-to-back wins for the first time since December with a 1-0 victory over Reading.