Leipzig's Yussuf Poulsen and team mates form a wall to defend a set piece taken by Monaco's Joao Moutinho in tgheir Champions League clash on Tuesday.
Monaco - Leipzig took full advantage of slack Monaco defending
Devastating RB Leipzig boosted their chances of qualifying for the last 16 of the ChampionsLeague on Tuesday by taking Monaco apart 4-1 with a four-goal first-half demolition that saw them draw level on points with second-place Porto in Group G.
Leipzig took full advantage of slack Monaco defending and Porto drawing 1-1 at Besiktas earlier on with a free-flowing attacking display that saw the Bundesliga side reignite their knockout hopes.
Ralph Hasenhuettl's team stay third due their head-to-head record, which has Porto on top, 5-4 over their two matches. Monaco are out of Europe after failing to win once and picking up just two points from their five matches.
"We were focused and the boys were really sharp. That was a very, very good performance, our best in the ChampionsLeague by some distance," Hasenhuettl told Sky.
"Timo Werner is deadly in front of goal. It won't be easy to have to win at home, but we'll do our best."
Monaco coach Leonardo Jardim, who guided the club to the French title and the last four of the ChampionsLeague last season, admitted his team simply hadn't performed well enough this term.
"We've always paid heavily for our errors in this group this year," said Jardim.
"We haven't been up to the level of such a competition, with three defeats at home and two draws away. We need to build a stronger team for next season."
Monaco needed a win to have any chance of qualifying but gifted Leipzig a sixth-minute lead when defender Jemerson sliced an innocuous Marcel Sabitzer cross past befuddled Monaco keeper Danijel Subasic.
After scoring the opener Jemerson turned provider for the opposition three minutes later, his weak pass out from the back easily intercepted by Kevin Kampl, who scampered forward before feeding Timo Werner with an easy chance that the German happily slotted home.
Monaco briefly rallied, and Radamel Falcao was unlucky to see his close range stab at goal, after confusion in the Leipzig defence, kicked away by RB stopper Peter Gulacsi, but the Colombian soon had an impact at the other end, clumsily bringing down Willi Orban in his own area and allowing Werner to double his tally from the penalty spot.
Falcao made up for his mistake two minutes before the break when he met Rony Lopes' free-kick before Gulacsi could connect with his fist to reduce the deficit to two.
But the striker's struggling teammates let him down only with seconds of the half to spare, with Naby Keita spinning Kamil Glik before charging towards goal and ending Monaco's European hopes with a neat finish.
Monaco, fresh from a domestic disappointment after a draw at Ligue 1 new boys Amiens at the weekend, failed to rally, and Leipzig cruised to a win that gives them a chance of qualifying from the group.
They host leaders Besiktas on December 6 needing to do better than Porto do at home to rock-bottom Monaco.