Michael Gregoritsch scored on his Schalke 04 debut and helped set up the other goal as they beat second-placed Borussia Monchengladbach 2-0 on Friday as action in the Bundesliga resumed following the winter break.
David Wagner's team turned up the heat after half-time with Suat Serdar slotting in from a Gregoritsch pass in the 48th minute.
The Austrian, who joined Schalke during the winter break on loan from Augsburg, then finished off a fine break 10 minutes later, tapping in Benito Raman's assist to lift Schalke to fourth place on 33 points.
They are level with champions Bayern Munich, who take on Hertha Berlin on Sunday.
League leaders RB Leipzig, on 37, host Union Berlin on Saturday. Gladbach remain in second place on 35.