Peterborough claimed a crucial win in the race for the Sky Bet League One play-offs by beating fellow promotion hopefuls Derby 2-0.
Second-half goals from Ephron Mason-Clark and Nathanael Ogbeta settled the contest and moved Darren Ferguson's men to within a point of the top six.
Derby, who kicked off four points clear of their hosts, provided the only attempt on target of the first half when Conor Hourihane was denied by the boot of Posh keeper Will Norris.
But it was a different story after the break as Mason-Clark rifled a 52nd-minute opener past County keeper Joe Wildsmith after being picked out by a Jack Taylor pass.
Ogbeta, Jonson Clarke-Harris and Taylor were all then denied by smart Wildsmith saves.
Substitute Tom Barkhuizen squandered County's best chance to level when nodding a Louie Sibley cross just over from close range.
And that proved costly as a second Posh goal arrived moments later in the 82nd minute when Ogbeta was on hand to tuck away his first for the club after Kwame Poku was kept out by Wildsmith.