Chris Wood's first half goal gave Leeds a vital 1-0 win over Sheffield Wednesday, who missed a penalty through Jordan Rhodes at Elland Road on Saturday.
Wood poked home from six yards halfway through the first half after some poor Wednesday defending, his 23rd goal in all competitions for Leeds this season.
Rhodes then saw his penalty tipped onto the post by Rob Green, after Sam Hutchinson had been hauled down in the area by Souleymane Doukara.
Leeds held on despite late Wednesday pressure, and move into fourth place, nine points clear of seventh-place Fulham having played two games more.
In a first-half lacking in chances, Wednesday's defence gifted Wood an opener on 24 minutes, the striker converting in space from six yards for his 20th league goal after Vincent Sasso had opted not to clear Gaetano Berardi's cross from the left.
Wednesday went close shortly after as Wood nearly deflected Ross Wallace's fine cross into his own net, and after the break the hosts had a strong penalty shout turned down after Hutchinson hauled down Eunan O'Kane on the right of the area.
Wednesday got a spot-kick of their own on 54 minutes as Doukara hauled down Hutchinson inside the box, but Rhodes stepped up to see his effort tipped onto the post superbly by Green.
Rhodes then headed just over from the resulting corner, while at the other end Kemar Roofe and Pablo Hernandez got in each other's way as the latter poked the ball just wide of the Wednesday post.
Leeds saw the game out, and after two straight defeats earlier in February, have now taken seven points out of their last possible nine.
Leeds boss Garry Monk:
"We were playing a very good side in Sheffield Wednesday. I thought they put some pressure on but we dealt with it extremely well. I can't remember them having any shots on goal apart from the penalty so that was very pleasing.
"The pressure that's there to win these types of games, both teams on the same points, a derby game. I thought we handled the pressure really well today and I'm very pleased with the players."
Sheffield Wednesday boss Carlos Carvalhal:
"We didn't lose today because we didn't try. We fought a lot and created a big chance with the penalty.
"We win together and we lose together. The responsibility is not too any one player. Individual mistakes are part of the game and we must understand them. It is normal in football."