First-half goals from Ayegbeni Yakubu and Andy King sealed victory for play-off chasing Leicester at Derby.
On-loan forward Yakubu found the net midway through the half with a powerful volley from 12-yards out.
And King sealed the points in first-half injury time with a neat finish from just inside the area after latching onto Paul Gallagher pass.
Victory lifted Leicester up to seventh and four points off sixth-placed Leeds in the play-off zone.
The home defeat for Derby piles more pressure on boss Nigel Clough and leaves the Rams languishing in 17th place in the table, without a win in six league games.
Leicester looked the livelier of the two teams in the opening exchanges and after Paul Gallagher sent Patrick Van Aanholt through with a clever pass that split the Rams defence, the Chelsea loanee fizzed the ball across the face of the goal but Yakubu could not stretch far enough to convert from close range.
The visitors broke the deadlock when Yakubu took advantage of some poor Derby defending to fire into the top corner with a smart left-footed volley on the turn.
Gallagher almost doubled the Foxes' advantage on the half hour but his curling shot from the edge of the box flew agonisingly past the post.
The home side showed no signs of troubling debutant Pereira Ricardo in the Leicester goal as the visitors did all the pressing in the first period and were rewarded with their second goal on the stroke of half-time.
King latched on to a perfectly weighted through ball from Gallagher to slot past Stephen Bywater following impressive build-up play involving Van Aanholt and Yakubu.
Derby were disappointed not to be awarded a penalty a minute after the restart when Steve Davies' free-kick was blocked by a Leicester player's hand in the area but the referee waved play on.
The game was held up for five minutes as central defenders Ben Mee and Souleymane Bamba both received treatment after clashing heads on the edge of their penalty area but when the contest restarted, the Foxes showed no signs of stopping as they passed the ball around fluently.
The Rams, who lacked creativity in the final third, tried in vain to find a way back into the game but were thwarted by an impressive Foxes backline, who were influential in Leicester's victory.
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