Lech Poznan capitalised on Ektraklasa leaders Legia Warsaw's slip-up with a 1-0 win at Korona Kielce on Sunday.
With Legia suffering a 1-0 away defeat to Slask Wroclaw, Bartosz Slusarski's second-half winner saw Lech take full advantage to close within four points of top place.
Kielce more than held their own in freezing temperatures in southern Poland and it took Poznan 72 minutes to break the deadlock.
Substitute Slusarski's impact was almost immediate as he beat the offside trap to slot in his fourth goal in as many games.
Kielce have won just once in six matches and stay 13th in the standings.
The Ekstraklasa enters the winter break and will resume February 23.