Forward Yoshinori Muto helped secure Mainz's survival in the German top-tier on Saturday by scoring in the team's 2-1 victory at Borussia Dortmund.
After Bote Baku opened the scoring for Mainz in the fourth minute, Muto doubled the lead with his eighth goal of the season nine minutes later, ensuring Mainz a place in next season's top flight with one game remaining.
The win at a sellout Signal Westfalenstadion took Mainz's points haul to 36 points from 33 matches, leaving it 14th in the 18-team table.
"I don't think scoring eight goals as a forward is a lot," said Muto, Mainz's top scorer. "It'll be great if I can score two more goals in our final match and reach double digits."
Dortmund entered the match needing a win to secure a spot in next season's UEFA Champions League. It halved the deficit through Maximilian Philipp in the 16th minute, but the hosts were denied shooting opportunities for much of the second half by Mainz defenders.
Dortmund will visit Hoffenheim in their final weekend of the season, needing a point to be sure of its place in next season's Champions League.
In the Spanish first division, Takashi Inui scored his fifth goal of the season and set up another in Eibar's 4-1 win at Girona.