Peter Stoger won his first match as Borussia Dortmund manager as victory over Mainz gave them their first Bundesliga success since September.
Sokratis Papastathopoulos and Shinji Kagawa scored to secure a win that moved Dortmund up into fourth place.
Former Cologne manager Stoger replaced Peter Bosz on Sunday after the Dutchman was dismissed following a run of one win in 13 matches.
Stoger was sacked by Cologne last week with the club bottom of the table.
Stoger, who left Cologne having not won a Bundesliga game this season, has described his new job as “the opportunity of a lifetime”.