Diego Demme and Marcel Sabitzer earned RB Leipzig a 2-0 victory at Zenit that edged Julian Nagelsmann's side closer to qualification for the last 16 of the Champions League.

Stand-in captain Demme rifled a fierce shot past Zenit goalkeeper Mikhail Kerzhakov in the fifth minute of first-half stoppage time to put Leipzig on the path to an important victory.

Nagelsmann's side put six goals past Wolfsburg in the DFB-Pokal last Wednesday and scored eight against Mainz at the weekend, but they lacked a clinical edge with Timo Werner starting on the bench due to a muscle complaint.

Werner, who scored five goals and assisted the same amount in those two resounding victories, came on in the 61st minute and played a role in Sabitzer ensuring they retained top spot in Group G regardless of the result between Lyon and Benfica later on Tuesday.

Leipzig thought they had taken the lead in the 14th minute when Marcel Halstenberg picked out the bottom-right corner from 20 yards, but referee Orel Grinfeld disallowed the goal upon review because the ball brushed Christopher Nkunku's arm in the build-up.

Douglas Santos almost won Zenit a penalty after the half-hour mark, though VAR confirmed the on-field decision to only award a free-kick.

Sardar Azmoun scuffed wide and Zenit paid the price when Sabitzer's free-kick was blocked and Demme drilled a fine follow-up effort home from 25 yards on the stroke of half-time.

Nkunku and Emil Forsberg were denied by Kerzhakov before Werner was sent on for the Frenchman.

Werner played a role in Leipzig's second goal in the 63rd minute, feeding Forsberg with a pass the Swede slid in behind for Sabitzer to finish at the near post.

Artem Dzyuba and Dayot Upamecano were booked for a heated confrontation before Peter Gulacsi produced a stunning stop to keep Yordan Osorio's header out of the top-left corner and secure the clean sheet.