The team which started the day second from bottom managed to defeat the side second from the top with a display of motivation and determination
An own goal from Nelson Muslera in the 39th minute put the visitors in front against a poor Lazio side.
The hosts improved early in the second half and levelled through Stefano Mauri just two minutes in, but Carlos Grossmuller grabbed a deserved winner for Lecce to give them three crucial points in their battle against relegation.
It was a forgettable first half for both sides with Lecce shading it only slightly, and that was reflected in the scoreline.
Jeda's shot in the 39th minute landed plum on the right-hand post from where it rebounded against Muslera's back and, subsequently, into the net.
Lazio needed to improve and they did with Mauri bringing them level in the 47th minute.
It was a rather scrappy goal, in keeping with the game in general, with the ball taking a few rebounds inside the penalty area before arriving at Mauri, who somehow sliced it in from a few yards out.
Grossmuller missed the chance to put Lecce back in front in the 55th minute when he sidefooted a weak shot straight at Muslera.
Mauro Zarate almost put Lazio in front when his corner hit the far post directly before Grossmuller scored with his next attempt.
Daniele Corvia missed a cross from the right, but Grossmuller's shot was accurate this time to beat Muslera.
Lecce should even have grabbed a third in the 84th minute, but the ball somehow stayed out after Jeda's shot was cleared off the line by Giuseppe Biava, Gianni Munari then headed the ball against the crossbar from just a foot out and Jeda shot wide on the next rebound.
Lazio were unable to get a leveller and failed to take advantage of AC Milan's stumble against Udinese as they fell six points behind the Rossoneri at the top.
Lecce moved up one position, leaping above Brescia and closer to safety.