Mainz continued their impressive rise from last spot to mid-table safety with a 2-1 home win over Eintracht Frankfurt in the Bundesliga on Sunday.
Paul Nebel's 89th-minute winner gave Mainz all three points after Frankfurt's Nathaniel Brown had equalised for the visitors in the 20th minute, cancelling out Nebel's early opener.
Stranded in last spot when former Union Berlin coach Urs Fischer took over in December, Mainz have since lost just two of 18 matches in all competitions and sit 11th in the Bundesliga, six points above the relegation play-off spot.
They are through to the quarterfinals of a European competition for the first time after beating Sigma Olmutz in the UEFA Conference League on Thursday.
Later on, Sunday, St Pauli can move out of the bottom three with a win at home to Freiburg while Champions League hopefuls Stuttgart can move into outright third spot by avoiding defeat at Augsburg.