Champions League semi-finalists in 2020, RB Leipzig are struggling under American coach Jesse Marsch to maintain the form that took them close to the pinnacle of European football.

Leipzig host Paris Saint-Germain on Wednesday in a repeat of their 2020 semi-final won by the French champions, who also beat the Germans in Paris earlier in this season's group stage a fortnight ago.

Marsch, 47, replaced Julian Nagelsmann who left to join Bayern Munich afer last season.

Despite steering sister club Red Bull Salzburg to the Austrian league and cup double in each of the last two seasons, Marsch has cut a frustrated figure as Leipzig have posted inconsistent results.

"Obviously we had imagined a very different start to the season," admitted CEO Oliver Mintzlaff, who has backed Marsch to steady the ship after three Champions League defeats.

"We were well aware that it would take some time after so many changes both to the team and coaching staff and changes off the pitch."

Saturday's 1-1 draw at Eintracht Frankfurt meant Leipzig missed out on fourth place in the Bundesliga after leaking a last-gasp equaliser.

"It was crazy, we had everything under control, but the forwards missed a lot of chances and we made too many mistakes," Marsch fumed.

His appraisal of Saturday's game could also sum up Leipzig's season.

Founded in 2009 and backed by the deep pockets of Austrian drinks giants Red Bull, RB Leipzig flew up through the German football pyramid to reach the Bundesliga for the 2016/17 season.

Rather than signing big names, shrewd recruiting brought in Timo Werner, before he left to join Chelsea, Yussuf Poulsen, Emil Forsberg and Peter Gulacsi.

Yet outside Saxony, RB Leipzig is unpopular with German fans.

RB Leipzig has bent the German league's '50+1' rule - designed to stop a backer owning a controlling share - as most of their small number of members have direct links to Red Bull.

Even the name evades a ban on a sponsor appearing in a club's title as 'RasenBallsport' (LawnBallsport) is a fabricated German word which often leads to them being incorrectly refered to as 'Red Bull Leipzig'.

Critics accuse Red Bull of manufacturing a club to promote their products.

Dortmund CEO Hans-Joachim Watzke has accused RB Leipzig of only existing to sell cans of energy drink.

Nevertheless, RB Leipzig have proved a model club, twice runners up in the Bundesliga behind Bayern Munich and never finishing outside the top six during their time in Germany's top flight.

They are currently eighth under Marsch.

It looked like the transition after Nagelsmann would be smooth when they thrashed Stuttgart 4-0 at the start of the season.

Then came defeats to Wolfsburg and Bayern before Leipzig were crushed 6-3 at Manchester City in the Champions League.

"Maybe it's not fair that we have such big tests now like against Bayern and away at Manchester," said an exasperated Marsch at the time.

Leipzig bounced back and whipped Hertha Berlin 6-0 in the Bundesliga.

Then they lost 2-1 at home to Brugge before leading PSG at the Parc des Princes only for Lionel Messi to exploit basic mistakes and score twice as Leipzig lost 3-2.

Four days after going down fighting in Paris, they struggled badly at home to Greuther Fuerth before late goals sealed a 4-1 win.

Marsch rated Leipzig's plucky performance in Paris as their "best of the season" but a fourth defeat on Wednesday will be the final nail in their Champions League hopes this season.