Erling Braut Haaland scored twice on his return from injury as Borussia Dortmund went top of the Bundesliga with victory over Mainz.
Marco Reus had already put Dortmund ahead when the Norwegian forward, who had been out since late September with a muscle injury, scored a penalty, awarded for handball.
Jonathan Burkardt scored to narrow the deficit late on.
But Haaland settled the match with his second in added time.
The 21-year-old has now scored a remarkable 49 times in 49 league matches for Dortmund and 70 goals in 68 matches in all competitions.
"It is clear he had been missing in our team," Dortmund captain Reus said. "It is important that he plays because he constantly keeps two or three players occupied.
"To score two goals on his comeback is top. That is why we signed him."
The win was Dortmund's ninth in succession at home and takes them two points clear of reigning champions Bayern Munich, who are away at third-placed Bayer Leverkusen on Sunday.