Brennan Johnson scored the only goal as Nottingham Forest beat Leeds to move six points clear of the relegation places.
Forest were second best throughout the first half but led at the break thanks to Johnson's thumping 14th-minute strike.
After Leeds failed to clear a free-kick on the right, the ball bounced up for the Wales forward to rifle it into the bottom corner from the edge of the box.
The hosts were indebted to debutant goalkeeper Keylor Navas, on loan from Paris St-Germain, who made important first-half saves from Wilfried Gnonto, Luke Ayling and Luis Sinisterra, who put Leeds' best chance of the game over the bar from six yards out.