Leicester striker Martyn Waghorn increased the pressure on Reading manager Brendan Rodgers as his header ensured the Royals' nine-month wait for a home win in the Coca-Cola Championship continues following a 1-0 defeat.
Reading were on top for the majority of a tense game at the Madejski Stadium but saw forward Simon Church waste a catalogue of chances as Waghorn gave Nigel Pearson's side all three points.
Last year's League One champions Leicester move into the play-off places with this stolen win while the Royals remain in the relegation places.
Church, Jobi McAnuff and Grzegorz Rasiak all had presentable chances in a bright opening before Reading should have taken the lead in the 25th minute. Church released McAnuff and the winger hit a shot down into the turf which bounced past goalkeeper Chris Weale and into the far post.
McAnuff reacted well to hit the rebound toward goal but left-back Ryan McGivern made a fine block to keep the ball out.
Church then wasted the best chance of the half when Rasiak's flick sent him in on goal but the Wales international dragged his shot wide of Weale's post.
Church was denied by an excellent save from Weale moments later after an elaborate corner routine fell to him inside the area and had time for another shot off target before half-time.
But Leicester took the lead when Matt Oakley delivered a corner from the right and Waghorn got ahead of Gylfi Sigurdsson to flick a header over Federici and into the net.
Church missed another golden chance five minutes after the restart when he scuffed into the side-netting but Matty Fryatt could have doubled the lead at the other end when he beat the offside trap but could not beat Federici.
Reading's lack of a predatory goalscorer was again highlighted when McAnuff and then Ryan Bertrand cut balls across the face of a vacant goal as the crowd began to turn on Rodgers.
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