Emil Forsberg drilled in a second-half winner as RB Leipzig were made to work hard for a 1-0 victory over in-form Union Berlin on Wednesday that kept them on the heels of leaders Bayern Munich.
Sweden international Forsberg, who had come on 10 minutes earlier, fired in after a one-two with Dani Olmo to break the deadlock in the 70th minute after a largely toothless first half from the hosts.
Leipzig had to remain patient as Union worked hard to keep their opponents well away from the box.
The hosts upped the pressure after the break and Christopher Nkunku went close to scoring before Forsberg netted the winner and made sure of the three points.
"The boys were extremely mature mentally tonight," said Leipzig coach Julian Nagelsmann. "They kept their cool and they had the necessary patience which was important."
"We deserved the win in the end and we are satisfied with the first half of the season," he said.
Leipzig keeper Peter Gulacsi came to their rescue in stoppage time, palming a powerful shot from Marius Buelter wide.
The win lifted Leipzig to 35 points, four behind Bayern, who edged past Augsburg 1-0 to stay top at the season's halfway mark.
Union suffered their first loss in seven league games and dropped to sixth on 28.
(Reporting by Karolos Grohmann; Editing by Toby Davis)
